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McMahon, Brendan. "Deformation mechanisms beneath shallow foundations." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244367.
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Shallow foundations can provide the most economical solution for supporting small-scale structures. The design approach is quite simple considering the ultimate bearing capacity and working-load settlement. Research has shown that settlement calculations, determined using a linear-elastic approach, usually govern the design but this approach is inappropriate because soil is highly non-linear, even at small strains. The result is that signifi cant discrepancies are observed between predicted and actual settlements. This uncertainty has seen the development of settlement-based approaches such as Mobilisable Strength Design (MSD). MSD uses an assumed undrained mechanism and accounts for soil non-linearity by scaling a triaxial stress-strain curve to make direct predictions of footing load-settlement behaviour. Centrifuge experiments were conducted to investigate the mechanisms governing the settlement of shallow circular foundations on clay and saturated sand models. Clay model tests were performed on soft or rm kaolin beds, depending on its pre-consolidation. Sand model tests were performed on relatively loose Hostun sand saturated with methyl-cellulose to slow consolidation. One-dimensional actuators were developed to apply footing loads through dead-weight or pneumatic loading. A Perspex window in the centrifuge package allowed digital images to be captured of a central cross-section, during and after footing loading. These were used to deduce soil displacements by Particle Image Velocimetry which were consistent with footing settlements measured directly. Deformation mechanisms are presented for undrained penetration, consolidation due to transient flow, as measured by pore pressure transducers, and creep. A technique was developed for discriminating consolidation settlements from the varying rates of short and long-term creep of clay models. Using MSD, a method for predicting the undrained penetration of a spread foundation on clay was proposed, using database results alone, which then provided estimates of creep and consolidation settlements that follow. The importance of the undrained penetration necessitated further investigation by using the observed undrained mechanism as the basis of an ellipsoidal cavity expansion model. An upper-bound energy approach was used to determine the load-settlement behaviour of circular shallow foundations on linear-elastic and non-linear clays, with yield defined using the von Mises' yield criterion. Linear-elastic soil results were consistent with those obtained from nite element analyses. The non-linear model, as described by a power-law, showed good agreement with both centrifuge experiment results and some real case histories. The single design curve developed through this model for normalised footing pressure and settlement could be used by practising engineers based on existing soil correlations or site investigations.
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Rattley, Michael James. "The uplift behaviour of shallow foundations." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439346.
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Mangal, Jan Krishna. "Partially-drained loading of shallow foundations on sand." Thesis, University of Oxford, 1999. http://ora.ox.ac.uk/objects/uuid:205bf0bc-b801-4648-a556-8dba0d113cba.
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Wave loading on offshore structures founded on sand can result in partially drained response of the foundation soil. The characteristics of the rate of loading, the permeability of the soil, and the size of the foundation affect the degree of partial drainage. Partial drainage refers to situations where pore pressures develop in the soil, and the response of the soil is neither fully drained nor undrained. This thesis is concerned with the effects of loading rate, and consequent drainage, on the behaviour of a flat footing that is founded on the surface of a saturated sand base. The results of physical tests performed in the laboratory on a model-sized footing are reported. The footing was founded on oil-saturated fine sand and was subjected to combined loading. The effect of the vertical, horizontal, and rotational displacements are reported. The response of the footing is analysed in the context of existing drained foundation models that are based on work hardening plasticity theory. The rate dependency of the vertical load:deformation behaviour and the combined yield surfaces are described.
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Yilmaz, Mustafa Tolga. "Seismically Induced Tilting Potential Of Shallow Mats On Fine Soils." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605402/index.pdf.
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Occurrence of displacements of shallow mat foundations resting on saturated silt-clay mixtures were reported in Mexico City during 1985 Mexico Earthquake, and in Adapazari during 1999 Kocaeli (izmit) Earthquake. Soft surface soils, shallow ground water, limited foundation embedments and deep alluvial deposits were the common features pertaining to such foundation displacements in either case. Experience shows, while uniform foundation settlements, even when excessive, do not limit post earthquake serviceability of building structures, tilting is particularly problematic. In this study, a simplified methodology is developed to estimate the seismically induced irrecoverable tilting potential of shallow mats on fine saturated soils.
The undrained shear and deformation behavior of silt-clay mixtures encountered at the Adapazari sites with significant foundation displacements are investigated through a series of standard and rapid monotonic, and stress-controlled cyclic triaxial tests conducted over anisotropically consolidated natural soil samples. Test results show that, while the shear strength of these soils do not significantly degrade under means of loading comparable to that of Kocaeli earthquake, their plastic strain accumulation characteristics critically depend on the mode of loading as well as the relative levels of applied load with regard to the monotonic strength.
Based on the results of laboratory tests, the response of nonlinear soil-foundation-structure system is reduced to a single-degree-of-freedom oscillator with elastic-perfectly plastic behavior. The natural period of the system is expressed by simplified soil-structure-interaction equations. Pseudo-static yield acceleration, which is required to initiate the foundation bearing capacity failure when applied to the structural mass, is estimated by the finite-element method. Eventually, the tilting potential of the foundations is estimated utilizing inelastic response of the nonlinear oscillator. Response of the deep alluvium sites, which involves velocity pulses with periods consistent with the fundamental site period, is significant in determination of inelastic response of low bearing capacity systems.
Predictive capability of the methodology developed is tested with actual case data. The methodology is observed to predict irrecoverable tilting potential of foundations consistent with the observations, except for the cases with low seismic bearing capacity. Deviations are explained considering the sensitivity of low-strength systems to asymmetrical behavior and uncertainties involved in seismic demand.
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Yamamoto, Nobutaka. "Numerical analysis of shallow circular foundations on sands." University of Western Australia. School of Civil and Resource Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0038.
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This thesis describes a numerical investigation of shallow circular foundations resting on various types of soil, mainly siliceous and calcareous sands. An elasto-plastic constitutive model, namely the MIT-S1 model (Pestana, 1994), which can predict the rate independent behaviour of different types of soils ranging through uncemented sands, silts and clays, is used to simulating the compression, drained triaxial shear and shallow circular foundation responses. It is found that this model provides a reasonable fit to measured behaviour, particularly for highly compressible calcareous sands, because of the superior modelling of the volumetric compression. The features of the MIT-S1 model have been used to investigate the effects of density, stress level (or foundation size), inherent anisotropy and material type on the response of shallow foundations. It was found that the MIT-S1 model is able to distinguish responses on dilatant siliceous and compressible calcareous sands by relatively minor adjustment of the model parameters. Kinematic mechanisms extracted from finite element calculations show different deformation patterns typical for these sands, with a bulb of compressed material and punching shear for calcareous sand, and a classical rupture failure pattern accompanied by surface heave for siliceous sand. Moreover, it was observed that the classical failure pattern transforms gradually to a punching shear failure pattern as the foundation size increases. From this evidence, a dimensional transition between these failure mechanisms can be defined, referred to as the critical size. The critical size is also the limiting foundation size to apply conventional bearing capacity analyses. Alternative approaches are needed, focusing mainly on the soil compressibility, for shallow foundations greater than the critical size. Two approaches, 1-D compression and bearing modulus analyses, have been proposed for those foundation conditions. From the validations, the former is applicable for extremely large foundations, very loose soil conditions and highly compressible calcareous materials, while the latter is suitable for moderate levels of compressibility or foundation size. It is suggested that appropriate assessment of compression features is of great importance for shallow foundation analysis on sand.
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Rivera, Rojas Alfonso Jose. "Lateral response of stiff column-supported shallow foundations." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/100795.
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The mechanisms that control the lateral response of stiff column-supported shallow foundations, resulting from the application of horizontal load on shallow foundations supported by stiff columns, are uncertain. Stiff columns constructed in soft clayey soil have been used to support retaining walls and in such cases, the lateral thrust applied behind these geotechnical structures is a source of horizontal loading. For seismic events, stiff columns constructed in soft clayey soil have been used to support shallow foundations subjected to horizontal load coming from the upper structure of buildings. Due to its practical applications, it has become important to understand the consequences of subjecting a shallow foundation supported by stiff columns to horizontal load by identifying the factors that control the lateral response of such systems.
A series of centrifuge tests were carried out to examine the lateral response of stiff column-supported shallow foundations. The experimental trends suggested that the thickness of the coarse-granular mattress placed above the soil-column composite, called the Load Transfer Platform (LTP), controlled the lateral capacity and the overall lateral response of these systems. A numerical study using the finite element method confirmed the experimental trends. A parametric analysis was conducted with the purpose of investigating the influence of different geometry-based and material-based variables in the lateral response of these systems. The results of the parametric analysis further confirmed the importance of the thickness of the LTP in controlling the lateral response. The parametric results also emphasized the contribution of other variables to this lateral response, and these variables included the undrained shear strength of the soft clayey soil around the stiff columns, the stiff column diameter, and the spacing of the stiff columns after they are constructed in the soft clayey soil.Doctor of Philosophy
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Algie, Thomas Brian. "Nonlinear rotational behaviour of shallow foundations on cohesive soil." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/9084.
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The most recent version of the New Zealand design and loadings standard eliminated a clause for the design of rocking foundations. This thesis addresses that clause by presenting a strong argument for rocking shallow foundations in earthquake resistant design. The goals of the research were to perform large scale field experiments on rocking foundations, develop numerical models validated from those experiments, and produce a design guide for rocking shallow foundations on cohesive soil. Ultimately, this thesis investigates the nonlinear rotational behaviour of shallow foundations on cohesive soil. Field experiments were performed on an Auckland residual soil, predominantly clay. The experiment structure - a large scale steel frame - was excited first by an eccentric mass shaker and second by a quick release (snap-back) method. The results show that rocking foundations produce highly nonlinear moment-rotation behaviour and a well defined moment capacity. A hyperbolic equation is proposed in Chapter 4 utilising the initial stiffness and moment capacity to predict nonlinear pushover response. The results show that the initial stiffness should be based on an 'operational soil modulus' rather than a small strain soil modulus. Therefore, the reduction factor from the small strain modulus was around 0.6 for the experiment testing. Additionally, the experiments showed that rocking foundations demonstrate significant damping; snap-back experiments revealed an average damping ratio of around 30%. Experiment data validated two numerical models developed for this study: one, a finite element model in Abaqus and the other, a spring bed model in OpenSEES. The models showed that both forms of nonlinearity in rotating shallow foundations - geometric nonlinearity and material nonlinearity - should be considered in shallow foundation analysis. These models also confirmed the need for an 'operational soil modulus' on shallow foundation rocking, and analysis of varying vertical loads suggested that this reduction factor is dependent on the vertical factor of safety of the foundation. Lastly, two design methods are presented, a displacement-based method and a forcebased method, and two examples of rocking shear walls are given. The displacementbased method is the recommended option, and it is shown that design displacements and rotations compare well to time history analyses performed using the validated OpenSEES model.
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López, Ana Priscilla Paniagua. "Two- and three-dimentional bearing capacity of shallow foundations." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14406.
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Bertalot, Daniele. "Seismic behaviour of shallow foundations on layered liquefiable soils." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/53bafb56-6c1c-4d27-9c16-da196273dca1.
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Earthquakes have been historically perceived as one of the most damaging natural hazards. Seismic soil liquefaction is often one of the major sources of damage and disruptions, and has been observed to severely affect key lifelines. Settlement and tilting of shallow foundations resting on saturated sandy/silty soils has been repeatedly observed throughout the world as a consequence of liquefaction or softening of the foundation soil. Such settlements and tilts can render structures unusable, and homes uninhabitable, causing significant economic losses. Despite the undoubted relevance of this phenomenon, field data on the liquefaction induced settlement of shallow foundations are scarce. New data from 24 buildings that suffered settlement and tilting as a consequences of soil liquefaction during the February 27th 2010 Maule earthquake in Chile, are presented in this work to supplement the existing field cases database. Due to the complexity of this phenomenon, field data are not suffcient to fully understand the mechanisms controlling the settlement of structures resting on liquefied or softened ground.In this framework, centrifuge modelling provides a valuable tool for research by reproducing field conditions in a controlled environment. A series of 10 dynamic centrifuge tests were performed as part of this work. Thanks to the University of Dundee newly installed centrifuge-mounted servohydraulic earthquake simulator, scaled version of field earthquake motions were reproduced in the models tested, enhancing the reliability of experimental results. Particular attention was given to the effect of key parameters on the observed foundation settlement. These parameters are the bearing pressure of the foundation, the thickness of the liquefied soil layer and the soil's relative density. The effect of the soil layering pattern was also investigated, with particular attention to the effect of a low permeability soil crust overlying the liquefied soil. Results suggest that the excess pore pressure generation in the foundation soil is significantly influenced by the stress distribution due to the presence of the foundation itself. In particular, lower excess pore pressure where measured in soil subjected to high static shear stresses (i.e. below the edge of a footing). The soil stratification pattern, and the relative thicknesses of the liquefied and un-liquefied portions of the soil profile, were also found to play a crucial role in determining the seismic demand at foundation level and the type of failure mechanism leading to foundation settlement. Observed differences between centrifuge (i.e. field) and element testing soil response are also discussed. Experimental results are compared to field observations, with the aim of improving the current understanding of the behaviour of structures built on shallow foundations in the eventuality of seismic induced liquefaction of their foundation soil.
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Chen, Jou-Jun Robert. "Load and resistance factor design of shallow foundations for bridges." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44627.
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Load Factor Design (LFD), adopted by AASHTO in the mid-1970, is currently used for bridge superstructure design. However, the AASHTO specifications do not have any LFD provisions for foundations. In this study, a LFD format for the design of shallow foundations for bridges is developed.
Design equations for reliability analysis are formulated. Uncertainties in design parameters for ultimate and serviceability limit states are evaluated. A random field model is employed to investigate the combined inherent spatial variability and systematic error for serviceability limit state. Advanced first order second moment method is then used to compute reliability indices inherent in the current AASHTO specifications. Reliability indices for ultimate and serviceability limit states with different safety factors and dead to live load ratios are investigated. Reliability indices for ultimate limit state are found to be in the range of 2.3 to 3.4, for safety factors between 2 and 3. This is shown to be in good agreement with Meyerhof's conclusion (1970). Reliability indices for serviceability limit state are found to be in the range of 0.43 to 1.40, for ratios of allowable to actual settlement between 1.0 to 2.0. This appears to be in good agreement with what may be expected. Performance factors are then determined using target reliability indices selected on the basis of existing risk levels.
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Al-Bittar, Tamara. "Probabilistic analysis of shallow foundations resting on spatially varying soils." Nantes, 2012. http://archive.bu.univ-nantes.fr/pollux/show.action?id=17b61462-4bf8-4bbd-9c16-ad777ebd98ab.
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Cette thèse présente une analyse probabiliste de fondations superficielles reposant sur un sol variable spatialement et soumises à un chargement statique ou dynamique (sismique). Dans la première partie de cette thèse, le cas d'un chargement statique a été considéré. Dans cette partie, seule la variabilité spatiale du sol a été examinée et les propriétés du sol ont été modélisées par des champs aléatoires. Dans la littérature, la méthode de simulation de Monte-Carlo (MCS comme Monte Carlo Simulation) est généralement utilisée. Dans cette thèse, la méthodologie de développement par chaos polynomial creux (SPCE comme Sparse Polynomial Chaos Expansion) est employée. Cette méthode vise à remplacer le modèle élément fini/différence finie par un méta-modèle. Cela conduit (dans le cas présent des problèmes stochastiques à grande dimension) à une réduction significative du nombre d'appels du modèle déterministe. En outre, une utilisation combinée du SPCE et de l'analyse de sensibilité globale GSA (dénommée SPCE/GSA) est proposée pour réduire encore une fois le coût de l'analyse probabiliste pour les problèmes faisant intervenir un modèle déterministe coûteux. Dans la deuxième partie de cette thèse, le chargement sismique a été considéré dans l'analyse probabiliste. Dans cette partie, la variabilité spatiale du sol et/ou la variabilité temporelle du chargement sismique ont été prises en compte. Dans ce cas, le chargement sismique a été modélisé par un processus aléatoire. Les résultats numériques ont montré l'effet significatif de la variabilité temporelle du signal sismique dans l'analyse probabilisteThe aim of this thesis is to study the performance of shallow foundations resting on spatially varying soils and subjected to a static or a dynamic (seismic) loading using probabilistic approaches. In the first part of this thesis, a static loading was considered in the probabilistic analysis. In this part, only the soil spatial variability was considered and the soil parameters were modelled by random fields. In such cases, Monte Carlo Simulation (MCS) methodology is generally used in literature. In this thesis, the Sparse Polynomial Chaos Expansion (SPCE) methodology was employed. This methodology aims at replacing the finite element/finite difference deterministic model by a meta-model. This leads (in the present case of highly dimensional stochastic problems) to a significant reduction in the number of calls of the deterministic model with respect to the crude MCS methodology. Moreover, an efficient combined use of the SPCE methodology and the Global Sensitivity Analysis (GSA) was proposed. The aim is to reduce once again the probabilistic computation time for problems with expensive deterministic models. In the second part of this thesis, a seismic loading was considered. In this part, the soil spatial variability and/or the time variability of the earthquake Ground-Motion (GM) were considered. In this case, the earthquake GM was modelled by a random process. Both cases of a free field and a Soil-Structure Interaction (SSI) problem were investigated. The numerical results have shown the significant effect of the time variability of the earthquake GM in the probabilistic analysis
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Gamber, Nathan K. "Shallow foundation systems response to blast loading." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176319209.
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Quoc, Van Nguyen. "Numerical modelling of the undrained vertical bearing capacity of shallow foundations." University of Southern Queensland, Faculty of Engineering and Surveying, 2008. http://eprints.usq.edu.au/archive/00006257/.
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[Abstract]The bearing capacity of foundations is a fundamental problem in geotechnical engineering. For all structures placed on a soil foundation, geotechnical engineers must ensure that the soil has sufficient load carrying capacity so that the foundation does not collapse or become unstable under any conceivable loading. The ultimate bearing capacity is the magnitude of bearing pressure at which the supporting ground is expected to fail in shear, i.e. a collapse will take place.During the last fifty years various researchers have proposed approximate techniques to estimate the short term undrained bearing capacity of foundations. The majority of existing theories are not entirely rigorous and contain many underlying assumptions. As a consequence, current design practices include a great deal of empiricism. Throughout recent decades, there has also been a dramatic expansion in numerical techniques and analyses, however, very few rigorous numerical analyses have been performed todetermine the ultimate bearing capacity of undrained soils.In this study, finite element analysis has been used to analyse a range of bearing capacity problems in undrained soil. The numerical models account for a range of variablesincluding footing size, shape, embedment depth, soil layering and undrained bearing capacity of footings on slopes.By using the powerful ability of computers a comprehensive set of solutions have been obtained therefore reducing the uncertainties apparent in previous solutions.
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Jones, Anthony James. "Analysis of shallow and deep foundations using soil-structure interaction techniques." Thesis, University of South Wales, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480929.
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Legaspi, Dante E. (Dante Evangelista). "Finite analyses to predict the performance of shallow foundations of clay." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11203.
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Ahmed, Ashraf. "Simplified and advanced approaches for the probabilistic analysis of shallow foundations." Nantes, 2012. http://archive.bu.univ-nantes.fr/pollux/show.action?id=dd487e61-a534-4e3e-a2f6-613819e93301.
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Cette thèse présente des approches simplifiées et avancées pour l’analyse probabiliste des fondations superficielles. Dans l'analyse probabiliste simplifiée, les paramètres incertains sont modélisés par des variables aléatoires. Pour une fondation soumise à un chargement incliné, les résultats numériques basés sur la méthode des surfaces de réponse (RSM) et la méthode des surfaces de réponse stochastiques (CSRSM) ont permis d'identifier les zones de prédominance des modes de rupture à l’état limite ultime et à l’état limite de service. D'autre part, une procédure efficace a été proposée pour augmenter le nombre des sorties probabilistes de l’approche Subset Simulation (SS) sans appels supplémentaires au modèle déterministe. Dans cette procédure, l'approche SS a été combinée avec la méthode CSRSM. Dans l'analyse probabiliste avancée, les paramètres incertains du sol sont modélisés par des champs aléatoires pour prendre en compte la variabilité spatiale des propriétés du sol. Dans ce cas, la méthode de simulation de Monte Carlo (MCS) est généralement utilisée et seuls les moments statistiques de la réponse sont étudiés en raison du grand nombre d'appels au modèle déterministe. Dans cette thèse, l'approche SS a d’abord été utilisée comme une méthode alternative à la méthode MCS pour calculer la probabilité de ruine. Ceci a conduit à une réduction significative du nombre d'appels au modèle déterministe. Ensuite, une approche plus efficace nommée improved Subset Simulation (iSS) a été développée pour réduire encore une fois le nombre d'appels au modèle déterministe. L'utilisation de l’iSS a réduit le nombre d'appels au modèle déterministe d'environ 50% par rapport à l'approche SSThis thesis presents simplified and advanced probabilistic analyses of shallow foundations. In the simplified probabilistic analysis, the uncertain parameters are modelled by random variables. For an obliquely loaded footing, the numerical results based on the Response Surface Method (RSM) and the Collocation-based Stochastic Response Surface Method (CSRSM) have allowed to identify the zones of failure mode predominance at both the ultimate and serviceability limit states. On the other hand, an efficient procedure was proposed to increase the number of the probabilistic outputs of the Subset Simulation (SS) approach with no additional time cost. In this procedure, the SS approach was combined with the CSRSM. In the advanced probabilistic analysis, the uncertain parameters are modelled by random fields to take into account the soil spatial variability. In such cases, Monte Carlo Simulation (MCS) methodology is generally used in literature. Only the statistical moments were generally investigated in literature because of the great number of calls of the deterministic model required by this method. In this thesis, the subset simulation approach was first used as alternative to MCS methodology to compute the failure probability. This leads to a significant reduction in the number of calls of the deterministic model. Moreover, a more efficient approach called improved Subset Simulation (iSS) approach was developed to reduce again the number of calls of the deterministic model. The use of the iSS approach has reduced the number of calls of the deterministic model by about 50% with respect to the SS approach
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Heron, Charles Michael. "The dynamic soil structure interaction of shallow foundations on dry sand beds." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/265576.
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The design of shallow foundations located in seismically active zones typically takes a near zero tolerance approach to allowing relative movements between the foundation and underlying soil. This results in a rigid coupling of the foundation with the soil and hence the full transmission of the seismic energy into the foundation. Consequently the structure located on the foundation either has to be isolated from the shaking through manufactured damping systems or designed to withstand the full force of the dynamic shaking while the energy is dissipated through structural damping. There is, however, an increasing focus on reducing the coupling between the soil and foundation which consequently reduces the demands on the structure. Allowing the foundation to slide and/or rock isolates the foundation from the dynamic shaking and helps to dissipate energy through soil damping. The same level of seismic protection which is currently provided by manufactured solutions is still therefore possible but with the advantage of reduced costs and complexity in construction. This design concept has, however, not been widely adopted due to concerns regarding the possibility for excessive movement of the foundation, resulting in damage to the superstructure or overall toppling of the structure. In addition, the behaviour is currently difficult to model precisely and therefore it is challenging to quantify the exact level of seismic protection achieved. The work presented in this thesis strives to address some of these issues. A series of ten centrifuge tests were conducted on small-scale model structures founded on dry sand and subjected to a series of simulated earthquakes. The effect of a range of model parameters was investigated including relative density, bearing pressure, structural stiffness, aspect ratio, earthquake strength and earthquake frequency. For six of the tests, the movement of the soil beneath the foundation and the structure itself were monitored by analysing images collected from high speed photography (1000 frames per second) using particle image velocimetry software. In addition to the photogramrnetry, a series of miniature measurement transducers were used to record the acceleration in the soil and the structure. Displacement transducers were used to monitor the settlement of the structure and free-field. In total over one hundred earthquakes were carried out resulting in an extensive dataset, against which hypotheses and analytical models could be verified. It was found that the transition from the structure being stationary to it responding in a steady state fashion can be a critical period in which the response of the soil-foundation-structure system must be carefully analysed. The phase shift between the superstructure, foundation and soil can vary during this period. As a result, different modes of response are adopted by the system which, in certain circumstances, can result in a significant increase in the displacement magnitude experienced by the structure. The behaviour is not unexpected, as the same behaviour can be observed from the analytical analysis of a simple single degree of freedom system. Inaddition, a strong correlation between rocking, sliding and settlement was observed, with the degree of lift-off controlling the amount of settlement and sliding which takes place. A macro-element analytical model has been developed to predict the moment-rotation behaviour of shallow raft foundations. A hyperbolic model, used for predicting the stress-strain behaviour of soil, was adapted and used to create the backbone curve of the moment-rotation cycle. A modification was made to the hysteretic damping rules proposed by Masing which allows the energy dissipation to be included in the model. The model was found to mimic the experimental data accurately, with the correct prediction of the lift-off rotation magnitude, moment magnitude, small-rotation stiffness and energy dissipation. Finally, the soil deformation mechanism was observed and analysed. It was found that in some scenarios, when the strain level within the deformation mechanism was low, a trapped wedge was apparent under the foundation. The trapped wedge appeared as a triangular zone of low strain (referred to in some literature as a rigid block), with the foundation located along the top edge and two distinct shear bands on either side. However, as strain magnitudes increased, the shear bands appeared to widen and resulted in strain being apparent throughout the previously unstrained wedge. One of the main differences between the theoretical mechanisms proposed in the literature is the inclusion or exclusion of such a rigid block. Given the majority of the analytical mechanisms proposed in the literature are upper bound mechanisms, and therefore are a prediction of the mechanism at failure, it is inadvisable to include the rigid wedge within the analytical mechanism given that the strain magnitudes will inevitably be large at the point of bearing failure. Given complete failure of the supporting soil did not occur during any of the centrifuge tests performed, comparisons between the observed mechanism and one of these theoretical mechanisms is difficult. However, comparisons between the experimental deformation mechanisms and one analytical failure mechanism did show that the depth of the mechanism could be relatively well predicted as could the degree of separation between the foundation and the underlying soil. This information allows design engineers to know to what depth ground should be remediated below a shallow foundation and how strong the foundation needs to be to cope with the lift-off it will experience. The insight provided by this research into the true soil deformation mechanism, combined with the development of an analytical model of the moment-rotation behaviour, paves the way for engineers to implement designs which actively make use of the beneficial characteristics of soil-structure-interaction.
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Fourtounis, Peter D. "Field-test data from soil-structure interaction of shallow and deep foundations." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1587896.
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This thesis presents an analysis of data from two soil-structure interaction field tests, one involving a deep foundation and the other a shallow foundation. The objective of this research is to use the field data to validate and inform models used by engineers. Soil-structure interaction fundamentals and background are first discussed. Field-test data was used in conjunction with a soil-structure system model to develop equations that can be used to determine stiffness and damping of a rigid pile foundation system subjected to forced vibration loading. The stiffness and damping characteristics are presented through complex-valued impedance functions. The equations were applied to field data; however the results were inconclusive due in part to the limited frequency range of the data used. Additionally, soil-foundation interface pressures are analyzed for a shallow foundation system. Analysis of the shallow foundation behavior indicated resonance of the field test structure and the corresponding pressure generation.
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Chong, Song Hun. "The effect of subsurface mass loss on the response of shallow foundations." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54271.
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Subsurface volume loss takes place in many geotechnical situations, and it is inherently accompanied by complex stress and displacement fields that may influence the performance of engineered geosystems. This research is a deformation-centered analysis, it depends on soil compressibility and it is implemented using finite elements.
Soil stiffness plays a central role in predicting ground deformation. First, an enhanced Terzaghi’s soil compressibility model is proposed to satisfy asymptotic conditions at low and high stress levels with a small number of physically meaningful parameters. Then, the difference between small and large strain stiffness is explored using published small and large-strain stress-strain data. Typically, emphasis is placed on the laboratory-measured stiffness or compressibility; however, there are pronounced differences between laboratory measurements and field values, in part due to seating effects that prevail in small-thickness oedometer specimens. Many geosystems are subjected to repetitive loads; volumetric strains induced by drained repetitive ko-loads are experimentally investigated to identify shakedown and associated terminal density.
The finite element numerical simulation environment is used to explore the effect of localized subsurface mass loss on free-surface deformation and shallow foundations settlement and bearing capacity. A stress relaxation module is developed to reproduce the change in stress associated to dissolution features and soft zone formation. The comprehensive parametric study is summarized in terms of dimensionless ratios that can be readily used for engineering applications.
Field settlement data gathered at the Savannah River Site SRS are back-analyzed to compare measured values with predictions based on in situ shear wave velocity and strain-dependent stiffness reduction. The calibrated model is used to estimate additional settlements due to the pre-existing cavities, new cavities, and potential seismic events during the design life of the facility.
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Elsayed, Ahmed L. "A new approach for non-linear load-settlement assessment of shallow foundations." abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453588.
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Kuo, Steven. "Scale Model Shake Table Testing of Shallow Embedded Foundations in Soft Clay." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/839.
Full textAbstract:
This research involves shake table testing of 1g scale models that mimic the coupled seismic response of a structure on a shallow mat foundation and foundation soil (known as soil-foundation-structural-interaction or SFSI). In previous research, SFSI effects have been quantified through analytical models, numerical analyses, and limited field data. This research works towards increasing the amount of empirical data through scale model shake table testing. A suite of earthquake time histories is considered in evaluating a nominal 10th scale soil-structure model using a flexible wall barrel on a 1-D shake table. San Francisco Young Bay Mud (YBM) is used as the prototype soil and long period narrow building as the prototype structure. Foundation embedment depth, fundamental mode of the structure, and seismic loading function are varied to generate a large database of SFSI results under controlled conditions. The foundation level response is compared to free-field responses to determine the magnitude of the SFSI.
The results confirm the effects of foundation embedment on the peak ground motion and the spectral acceleration at the predominant period of the structure. The foundation level accelerations are deamplified compared to free-field results. Results also confirm the legitimacy of the testing platform and program by comparing the data to previous experimental study.
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Vimalaraj, Panchalingam. "A simple equation for bearing capacity of a shallow foundation." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438933.
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Meranda, Jill L. "Analysis of Spread Footing Foundations as a Highway Bridge Alternative." Ohio University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1132692323.
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Al-Aghbari, Mohammed Yousuf Saif. "Bearing capacity of shallow strip foundations with structural skirts resting on dense sand." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367023.
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VALVERDE, NILTHSON NORENA. "3D ELASTOPLASTIC ANALYSIS FOR SHALLOW FOUNDATIONS AND EMBANKMENTS BY THE FINITE ELEMENT METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33096@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE EXCELENCIA ACADEMICA
BOLSA NOTA 10
A grande maioria das obras geotécnicas, tais como algumas fundações, aterros e escavações, apresentam uma configuração geométrica tipicamente tridimensional. No entanto, em função da complexidade da obtenção de soluções considerando os aspectos inerentes à condição de deformação e tensão tridimensionais, as análises destas obras têm sido comumente realizadas adotando-se as aproximações de deformação plana e/ou axissimétrica. Esta dissertação apresenta um modelo computacional baseado na formulação em deslocamento do método dos elementos finitos para a simulação de problemas mecânicos de equilíbrio estático de obras geotécnicas em condição tridimensional. São ressaltados os problemas de capacidade de carga de fundações superficiais e a simulação da construção de aterros. O solo é considerado como um material não linear elasto-plástico e os modelos não associados Mohr-Coulomb modificado e Lade-Kim são adotados para representar sua relação tensão-deformação resistência. As estratégias de solução não linear, tanto a nível global quanto em nível de ponto de Gauss, são apresentadas e discutidas. Os exemplos de capacidade de carga das fundações superficiais são comparados com os resultados da teoria do equilíbrio limite e da análise limite indicando bons resultados. O efeito da tensão intermediária na trajetória de tensão é apresentado e discutido nos exemplos de simulação da construção de aterros.
The vast majority of geotechnical works, such as some foundations, embankments and excavations, show a typical three-dimensional geometric configuration. However, depending on the complexity of obtaining solutions considering the aspects inherent to the three-dimensional deformation and stress, the analysis of these works have been performed by adopting common approaches and plane strain or axisymmetric. This dissertation presents a computational model based on displacement formulation of finite element method for simulation of mechanical problems of static equilibrium condition of geotechnical works in three dimensions. It highlights the problems of load capacity of shallow foundations and the simulation of embankment construction. The soil is considered as material non-linear elastic-plastic models and non-associated Mohr- Coulomb and modified Lade-Kim are adopted to represent their relationship stress-strain-resistance. The nonlinear solution strategies, both overall and in the Gauss point level, are presented and discussed. Examples of load capacity of shallow foundations are compared with the results of the theory of limit equilibrium and limit analysis showing good results. The effect of tension in the intermediate stress path is presented and discussed in the simulation examples of the construction of embankments.
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Archer, Andre. "Using small-strain stiffness to predict the settlement of shallow foundations on sand." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/43358.
Full textAbstract:
Settlement prediction of shallow foundations is an essential part for the design of a structure. Accuracy is important, and to increase the accuracy, reliable input parameters are required. However, reliable input parameters do not necessarily render accurate results since the parameters used in design are only as good as the prediction method. Foundation design on sands consists of two aspects: bearing capacity and settlement, with settlement being the governing factor in almost all cases. Settlement prediction is not always an easy task. The main reason being that engineers are unable to measure stiffness accurately as well as how to use the stiffness value measured in certain settlement methods. An important soil stiffness value is the initial small-strain shear modulus (G0) which can be obtained relatively easy with in-situ test methods and the values obtained are generally reliable. With in-situ testing becoming increasingly popular, settlement prediction methods utilising the initial small-strain shear stiffness are also becoming more common.
The main objective of this project is to determine whether the load-settlement behaviour of a shallow foundation can be estimated accurately using only the small-strain shear modulus of the granular soil below the foundation. Centrifuge tests were conducted on an equivalent 5m circular shallow foundation at three different density sands to establish if the stress-settlement behaviour can be predicted and to what level of accuracy. The different density sands were loose, medium dense and dense sands. Bender- and extender elements were used to determine the small-strain stiffness data which were used for the analysis.
The main conclusion drawn from the study is divided into two parts; Full-range load-settlement behaviour and Practical-range load-settlement behaviour. The full-range results relate to full stress-settlement curve with the practical-scale results up to settlements of 0.1D. The method proposed for the load-settlement prediction is a non-linear stepwise method. The proposed method requires utilising a stiffness degradation curve and it was found that curves presented by Oztoprak & Bolton (2013) and Bolton & Whittle (1999) produced the best results. For the full-range load-settlement results, accurate predictions were found between the predicted and measured load-settlement curves for low density sand. However accuracy decreases with increase in density. For settlements up to 0.1D the load-settlement behaviour was predicted with reasonably good accuracy.
The study showed that the settlement of a shallow foundation can be predicted with reasonable accuracy up to 0.1D settlement using only the small-strain shear stiffness value of the soil below the foundation and that there is merit in the proposed method for future use.Dissertation (MEng)--University of Pretoria, 2014.
lk2014
Civil Engineering
MEng
Unrestricted
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Shahin, Mohamed Amin. "Use of artificial neural networks for predicting settlement of shallow foundations on cohesionless soils." Title page, contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phs5254.pdf.
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"January 2003" Bibliography: p. 191-208. This thesis presents research which focuses on the settlement prediction of shallow foundations on cohesionless soils using artificial neural techniques. Previously, many methods have been developed to predict the settlement of shallow foundations, however methods that have the required degree of accuracy and consistency have not yet been developed. In this research artificial neural networks (ANNs) are used in an attempt to obtain more accurate settlement prediction. ANNs are linked with Monte Carlo simulation to provide a stochastic solution for settlement prediction that takes into account the uncertainties associated with settlement analysis. A set of stochastic design charts that provide the designer with the level of risk associated with predicted settlements are developed and provided.
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Elhakim, Amr F. "Evaluation of shallow foundation displacements using soil small-strain stiffness." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06242005-110638/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.Mayne, Paul, Committee Chair ; Puzrin, Alexander, Committee Member ; Germanovich, Leonid, Committee Member ; Lowell, Robert, Committee Member ; Rix, Glenn, Committee Member.
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Eyce, Bora. "An Investigation Of The Inertial Interaction Of Building Structures On Shallow Foundations With Simplified Soil-structure Interaction Analysis Methods." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610994/index.pdf.
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Seismic response of a structure is influenced by the inertial interaction between structure and deformable medium, on which the structure rests, due to flexibility and energy dissipation capability of the surrounding soil. The inertial interaction analyses can be performed by utilizing simplified soil-structure interaction (SSI) analyses methods. In literature, it is noted that varying soil conditions and
foundation types can be modeled by using these SSI approaches with springdashpot couples having certain stiffness and damping.
In this study, the seismic response of superstructure obtained by using simplified SSI methods is compared with those of the fixed base systems. For this purpose,
single and multi degree of freedom structural systems are modeled with both spring&ndashdashpot couple and fixed base models. Each system is analyzed for varying structural and soil stiffness conditions under the excitation of three different seismic records. Next, the total base shear acting on the structural system and internal forces of load bearing members are investigated to observe the inertial interaction and foundation uplift effects on the superstructure. It is also aimed to examine the compatibility of the simplified SSI approaches utilized in the analyses. It is concluded that the structural and soil stiffness parameters are the most influential parameters that affect seismic structural response. Structures becomemore sensitive to varying soil properties as the structural stiffness increases. On the other hand, decreasing soil stiffness also increases the sensitivity of the structure to the seismic excitation. Calculated values of total base shear and internal member forces revealed that the inertial interaction might be detrimental for the superstructure. Contrary to general belief, the fixed base approach does not always yield to the results, which are on the safe side. Considering the analysis results, it is concluded that SSI analysis is very useful for more precise and economical design for the seismic behavior.
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Nguyen-Sy, Lam. "The theoretical modelling of circular shallow foundation for offshore wind turbines." Thesis, University of Oxford, 2005. http://ora.ox.ac.uk/objects/uuid:fa4000fb-8de6-4093-b528-3e60d774dea0.
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Currently, much research is being directed at alternative energy sources to supply power for modern life of today and the future. One of the most promising sources is wind energy which can provide electrical power using wind turbines. The increase in the use of this type of energy requires greater consideration of design, installation and especially the cost of offshore wind turbines. This thesis will discuss the modelling of a novel type of shallow foundation for wind turbines under combined loads. The footing considered in this research is a circular caisson, which can be installed by the suction technique. The combined loads applied to this footing will be in three-dimensional space, with six degrees of freedom of external forces due to environmental conditions. At the same time, during the process of building up the model for a caisson, the theoretical analyses for shallow circular flat footing and spudcans also are established with the same principle. The responses of the soil will be considered in both elastic and plastic stages of behaviour, by using the framework of continuous plasticity based on thermodynamic principles. During this investigation, it is necessary to compare the numerical results with available experimental data to estimate suitable values of factors required to model each type of soil. There are five main goals of development of the model. Firstly, a new expression for plasticity theory which includes an experimentally determined single yield function is used to model the effects of combined cyclic loading of a circular footing on the behaviour of both sand and clay. This formulation based on thermodynamics allows the derivation of plastic solutions which automatically obey the laws of thermodynamics without any further assumptions. A result of this advantage is that non-associate plasticity, which is known to be a proper approximation for geotechnical material behaviour, is obtained logically and naturally. A FORTRAN source code called ISIS has been written as a tool for numerical analysis. Secondly, since there are some characteristics of the geometric shape and installation method which are quite different from that of spudcans and circular flat footing, another objective of this study is to adapt the current model which has been developed in ISIS for spudcans to the specific needs of caissons. The third goal of this research is the simulation of continuous loading history and a smooth transition in the stress-strain relationship from elastic to plastic behaviour. The model is developed from a single-yield-surface model to a continuous plasticity model (with an infinite number of yield surfaces) and then is discretized to a multiple-yield-surface model which can be implemented by numerical calculation to be able to capture with reasonable precision the hysteretic response of a foundation under cyclic loading. This can not be described by a conventional single-yield-surface model. Fourthly, as a method to simplify the numerical difficulties arising from the calculation process, a rate-dependent solution will be introduced. This modification is implemented by changing the dissipation function derived from the second law of thermodynamics. Finally, in order to control the model to capture the real behaviour, many parameters are proposed. A parametric study will be implemented to show the effects of these parameters on the solution.
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Oktay, Emre Hasan. "Finite Element Analysis Of Laboratory Model Experiments On Behavior Of Shallow Foundations Under General Loading." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614210/index.pdf.
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In this study, a series of laboratory model experiments carried on shallow foundations is intended to be simulated through numerical modeling. The laboratory model tests were conducted by Fukui et al. (2005), over square shaped, shallow surfacial foundations located over air-dried Toyoura sand. Tests included centered vertical and combined loading cases on sand with 60% and 80% relative densities. Plastic limit loads obtained from numerical analyses and available analytical solutions in literature are compared to the laboratory test results and the differences are discussed.
Employment of Mohr - Coulomb yield criterion and linear elasticity, resulting in linear elastic perfectly plastic constitutive law, is one of the most common practices in modeling geotechnical problems. Accuracy of this approach for the modeled experiments is judged by comparison of analyses results with experimental findings and solutions in literature. Finite element method is utilized for modeling purposes, with Mohr-Coulomb yield criterion and linear elastic behavior. Abaqus 6-10.2 is selected as the analysis software, and two and three dimensional models are used in the analyses. Analyses, the results of which are compared with experimental findings, aim employment of associated flow rule. Additional analyses are conducted with varying dilation angles in order to examine the influence of unassociated flow rule on eccentric and concentric loading results.
Differences between the results of numerical analyses and experimental observations varied between 2% and 34%. Main reason of the difference is attributed to employed soil behavior modeling approach in analyses and the eccentric placement of model weight in monotonic horizontal loading experiments. In the case when this eccentric placement is accounted for in numerical models, it is seen that the difference diminished to vary between 8% and 18%, and order of the difference was similar for similar experiment cases. Therefore, based on this condition, it is seen that results of the modeled experiments are consistent, while in general they are somewhat higher than the results obtained from analyses and solutions in literature. Difference between the results of analyses and average of selected solutions in literature in both cases is at most 9%.
Finite element method employing Mohr-Coulomb failure criterion could provide results in close agreement with solutions in literature that inherently assume Mohr-Coulomb failure criterion as well. However, the same accuracy could not be obtained for experiments due to uncertainties involved in the material properties as well as the insufficiencies of the model to represent the behavior precisely. Finite element method has the potential to consider more advanced material models. Nonetheless, employment of Mohr-Coulomb failure criterion provides results with sufficient accuracy for most cases.
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Khosravi, Mohammad. "Seismic Response of Structures on Shallow Foundations over Soft Clay Reinforced by Soil-Cement Grids." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/72978.
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This study uses dynamic centrifuge tests and three-dimensional (3D), nonlinear finite-difference analyses to: (1) evaluate the effect of soil-cement grid reinforcement on the seismic response of a deep soft soil profile, and (2) to examine the dynamic response of structures supported by shallow foundations on soft clay reinforced by soil-cement grids. The soil profile consisted of a 23-m-thick layer of lightly over-consolidated clay, underlain and overlain by thin layers of dense sand. Centrifuge models had two separate zones for a total of four different configurations: a zone without reinforcement, a zone with a "embedded" soil-cement grid which penetrated the lower dense sand layer and had a unit cell area replacement ratio Ar = 24%, a zone with an embedded grid with Ar = 33%, and a zone with a "floating" grid in the upper half of the clay layer with Ar = 33%. Models were subjected to a series of shaking events with peak base accelerations ranging from 0.005 to 0.54g. The results of centrifuge tests indicated that the soil-cement grid significantly stiffened the site compared to the site with no reinforcement, resulting in stronger accelerations at the ground surface for the input motions used in this study. The response of soil-cement grid reinforced soft soil depends on the area replacement ratio, depth of improvement and ground motion characteristics. The recorded responses of the structures and reinforced soil profiles were used to define the dynamic moment-rotation-settlement responses of the shallow foundations across the range of imposed shaking intensities. The results from centrifuge tests indicated that the soil-cement grids were effective at controlling foundation settlements for most cases; onset of more significant foundation settlements did develop for the weakest soil-cement grid configuration under the stronger shaking intensities which produced a rocking response of the structure and caused extensive crushing of the soil-cement near the edges of the shallow foundations. Results from dynamic centrifuge tests and numerical simulations were used to develop alternative analysis methods for predicting the demands imposed on the soil-cement grids by the inertial loads from the overlying structures and the kinematic loading from the soil profile's dynamic response.Ph. D.
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Ozyurt, Gokhan. "Cataloging And Statistical Evaluation Of Common Mistakes In Geotechnical Investigation Reports For Buildings On Shallow Foundations." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615084/index.pdf.
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Information presented in site investigation reports has a strong influence in design, project costs and safety. For this reason, both the quality and the reliability of site investigation reports are important. However in our country, geotechnical engineering is relegated to second place and site investigation studies, especially parcel-basis ground investigation worksdo not receive the attention they deserve. In this study, site investigation reports, that are required for the license of design projects, are examined and the missing/incorrect site investigations, laboratory tests, geotechnical evaluations and geotechnical suggestions that occur in the reports are catalogued. Also, frequency of each mistake is statistically examined
for geotechnical engineers, recommendations and solutions are presented to help them avoid frequent problems.
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Korec, Michael. "Založení nové a sanované podpěry "Starého mostu" přes Dunaj v Bratislavě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227604.
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The thesis is focused on the reconnstruction of the "Old Bridge“ in Bratislava. Part of the reconstruction is the foundations of a new pier and redevelopment of an existing pier. The introduction provides an overview of methods used for the foundations within the river and from there onwards, the most suitable method haas been selected. The piers foundation is designed in several variants, coupled with the drawings. In conclusion, the variants were compared and the most suitable one was selected.
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Skuodis, Šarūnas. "Faktorių, darančių įtaką pastato ir pagrindo sąveikai, vertinimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110610_160504-78001.
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Magistrinio darbo tikslas – įvertinti konstrukciją veikiančias apkrovas, apskaičiuoti konstrukcijos pamatų matmenis, apskaičiuoti pastato atskirų pamatų nuosėdžius, palyginti nuosėdžių reikšmes tarpusavyje, rasti santykinių nuosėdžių reikšmes ir įvertinti gretimų pamatų ir geologinių sąlygų nevienodumo įtaką šalia esantiems pamatams; įvertinti skirtingų smėlio frakcijų suspaudžiamumo savybes ir išskirti staigiųjų nuosėdžių dalį, atsirandančių smėliniuose gruntuose apkrovimo metu; pateikti išvadas bei pasiūlymus. Šiame darbe naudojami metodai, sprendiniai ir programos: sumavimo metodas, Businesko sprendinys, programos „STAAD.Pro“; „SCAD“, „MathCad“, „AutoCad“, „Exel“. Magistrinio darbo praktinė reikšmė – praplėsti supratimą apie konstrukcijas veikiančius faktorius, kurie gali labai skirtingai nulemti pagrindo ir pastato tarpusavio sąveiką. Pamatų nuosėdžių skaičiavimai parodė, kad atskirų pamatų nuosėdžiai bei santykiniai nuosėdžiai neviršija leistinų ribų, o gretimų pamatų įtaka gali būti nevertinama, kai atstumas tarp pamatų yra didesnis kaip 7,00 m. Smėlinių gruntų spūdumo savybių, dalelių formos įtakos, smėlinių gruntų elgsenos tyrimai parodė, kad smėliniuose gruntuose staigiosios deformacijos pasireiškia per pirmas 5 s, todėl galima teigti, kad statant statinius ant smėlinio grunto prognozuojami nuosėdžiai įvyksta statybos laikotarpiu.This masters work purpose is to estimate loadings in construction; calculate foundations dimensions; calculate separate foundations displacements; compare separate foundations displacements between themselves; find relative displacements values and estimate contiguous foundations via geological difference; estimate sand different partical size compression and find primary compression limits when soil is under load; present a report of calculations and laboratory investigations. In this final work was used Businesque problem, summing method and programs: “STAAD.Pro”, “MathCad”, “SCAD”, “AutoCad”, “Exel”. From practical view this work importance is to increase understanding of construction loadings and and factors influence on soil – structure interaction. Calculations of foundations displacements showed that separate foundations and contiguous foundations displacements did not reached their critical magnitudes. Contiguous foundations evaluation to each over could not be accounted then betweeen each over foundation is more than 7,00 m. Sand compression characteristics and sand fraction shape investigation showed that primary compression appears only in first 5 seconds. Because of primary compression all prognosis about total foundation displacement in sand soil estimates when construction is in building period.
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Chagas, Gleiber da Silva. "Estudo experimental do comportamento mecÃnico de estrato Silto- Argiloso (MassapÃ) para fundaÃÃes superficiais." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12231.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorO dimensionamento de fundaÃÃes superficiais requer definiÃÃo de forma clara e objetiva, para o solo em estudo, da capacidade de carga e a previsÃo dos recalques a que se submete a estrutura, baseando-se nas propriedades mecÃnicas obtidas por ensaios de laboratÃrio e campo. O ensaio de placa à uma das formas mais seguras para se obter essas informaÃÃes, a partir de carregamento direto, que produz, em escala reduzida, o comportamento da futura fundaÃÃo. Os ensaios realizados nesta pesquisa foram executados em trÃs etapas: caracterizaÃÃo geotÃcnica (granulometria, determinaÃÃo da massa especÃfica, limite de consistÃncia, compactaÃÃo proctor normal e Ãndice de suporte califÃrnia (ISC)); ensaios especiais de laboratÃrio (adensamento e cisalhamento); e ensaios de campo (provas de carga). O objetivo deste trabalho à avaliar a partir da realizaÃÃo de provas de carga diretas com solo na umidade natural e inundado, se previsÃes de potencial de colapso e expansÃo, realizadas a partir de ensaios edomÃtricos simples e duplos sÃo capazes de dar indicaÃÃes concordantes. Foi observado que resultados de ensaios edometricos duplos, realizados no solo silto argiloso da cidade de IcÃ, proporcionaram estimativas mais concordantes para as situaÃÃes de colapso do solo. AlÃm disso, a tÃcnica da compactaÃÃo de solos problemÃticos se mostrou adequada para minorar, ou mesmo anular, problemas relacionados ao colapso e a expansÃo do solo estudado.
The design of shallow foundations requires defining clearly and objectively to the soil under study, the load capacity and the prediction of settlements that undergoes structure, based on the mechanical properties obtained from laboratory testing and field. The plaque assay is one of the safest ways to get this information from direct loading, which produces, in reduced scale, the behavior of the Future Foundation. The tests performed in this study were performed in three steps: geotechnical characterization (particle size, density determination, consistency limits, standard Proctor compaction and California bearing ratio (ISC)); Special laboratory tests (density and shear); and field trials (load tests). The objective of this study is to evaluate the evidence from conducting direct load with soil and flooded in natural moisture, if forecasts of potential collapse and expansion, made from single and double edomÃtricos tests are able to give consistent evidence. It was observed that results of double edometricos trials, conducted in silty clay soil of the city Ico, provided more consistent estimates for situations of soil collapse. Furthermore, the technique of compression problematic soils was adequate to mitigate or even nullify, problems related to the collapse and expansion of the studied soil.
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Grzyb-Faddoul, Anna Marta. "Numerical analysis of the reinforcement of existing foundations by the Soil Mixing technique." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0141/document.
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L'objectif de ce travail est d'analyser l'influence du renforcement du sol par la method Soil Mixing sur le comportement des fondations superficielles et profondes. Une étude numérique a été effectuée – avec des analyses éléments finis dans ABAQUS - dans le but d'acquérir une compréhension du fonctionnement et une estimation de la performance des fondations améliorées. Pour être en mesure d'utiliser des colonnes SM pour l'amélioration de la fondation, il est nécessaire de bien comprendre leur performance sous charge axiale statique. Par conséquent, une série de simulations reproduisant des essais de chargement d'une seule colonne, et d’un groupe de colonnes ont été réalisées. Les essais à pleine et petite échelle ont été modélisés et leurs résultats comparés avec les observations expérimentales. Un bon accord entre les prédictions numériques et les mesures confirme une bonne calibration des lois constitutives des sols, des colonnes et de l’interface sol/colonne en SM. En outre, cette étude a révélé que la colonne SM agit d'une manière similaire à un pieu en béton, son comportement est régi principalement par l'interface. Ensuite, la modélisation numérique d’une fondation superficielle à petite échelle a été menée. Deux types de renforcement ont été étudiés. Le premier consiste en une seule colonne, située au centre sous la semelle analysée. Le second cas correspond à un groupe de quatre colonnes SM. Deux densités de sol ont été analysés. L'objectif de la modélisation est d'identifier l'efficacité du renforcement en termes de capacité portante de la fondation et de la réduction de son déplacement vertical. Il a été trouvé que la densité du sable a un impact significatif sur le comportement de la semelle. La variation de densité a entraîné une différence significative entre les forces totales portées par les fondations. Mais, il a été constaté que le pourcentage de la force reprise par le sol par rapport à la force total, est indépendant de la densité. L'influence du renforcement obtenu par un groupe de colonnes SM sur une fondation profonde, a été étudiée. La modélisation numérique d'un seul pieu théorique installé dans le sol homogène, a été réalisée. L'objectif de l'étude est de détecter l'impact de divers paramètres, tels que la distance horizontale entre les colonnes de SM, la distance verticale entre les têtes de colonnes et la pointe de pieu, le diamètre et la longueur des éléments SM, sur la capacité portante de la fondation. On a montré que la distance entre les colonnes et leur diamètre ont la plus grande influence sur la force de charge, la longueur de renforcement conduit à une moindre influenceThe aim of this work is to analyse the influence of soil reinforcement executed by the Soil Mixing method on the behaviour of shallow and deep foundations. Numerical investigation has been carried out - with the use of Finite Element (FE) analyses in ABAQUS - in an attempt to identify the mechanisms guiding the performance of supported foundations. To be able to use SM columns as the foundation’s improvement, it is necessary to fully understand their performance under applied static, axial load. Therefore, a set of simulations reproducing loading tests of single and group of columns have been carried out. Full and small scale tests have been modelled and their results compared with experimental observations. Good agreement between numerical predictions and measurements, confirms proper calibration of the chosen constitutive laws of: soils, columns and interactions between them. Moreover, this study has revealed that the SM column acts in a similar way to concrete pile, hence its behaviour is governed mainly by the interface. Afterwards, numerical modelling of small scale shallow foundation has been accomplished. Two kinds of reinforcement have been investigated. The first one consists of a single column situated centrally under the analysed footing. The second kind of improvement involves group of four SM columns. Two densities of soil have been analysed. The goal of the modelling is to identify the efficiency of the reinforcement in terms of: bearing capacity of the foundation and reduction of its vertical displacement. Despite significant difference between total forces borne by the foundation tested on soil with different densities, it has been found that the percentage of the total force that was taken by the soil is density independent. The influence of reinforcement executed by group of SM columns on a deep foundation has been studied. Numerical modelling of a theoretical, single pile, installed in homogeneous soil, has been carried out. The aim of the investigation is to detect the impact of parameters such as: pattern of reinforcing elements, horizontal distance between SM columns, vertical distance between columns’ heads and tip of the pile, diameter and length of SM elements, on the bearing capacity of the foundation. It has been found that the distance between columns and their diameter has the biggest influence on the borne force. However, the length of the reinforcement has shown the least significant influence
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Mohamed, Fathi Mohamed Omar. "Bearing Capacity and Settlement Behaviour of Footings Subjected to Static and Seismic Loading Conditions in Unsaturated Sandy Soils." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30661.
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Several studies were undertaken by various investigators during the last five decades to better understand the engineering behaviour of unsaturated soils. These studies are justified as more than 33% of soils worldwide are found in either arid or semi-arid regions with evaporation losses exceeding water infiltration. Due to this reason, the natural ground water table in these regions is typically at a greater depth and the soil above it is in a state of unsaturated conditions. Foundations of structures such as the housing subdivisions, multi-storey buildings, bridges, retaining walls, silos, and other infrastructure constructed in these regions in sandy soils are usually built within the unsaturated zone (i.e., vadose zone). Limited studies are reported in the literature to understand the influence of capillary stresses (i.e., matric suction) on the bearing capacity, settlement and liquefaction potential of unsaturated sands. The influence of matric suction in the unsaturated zone of the sandy soils is ignored while estimating or evaluating bearing capacity, settlement and liquefaction resistance in conventional engineering practice. The focus of the research presented in the thesis has been directed towards better understanding of these aspects and providing rational and yet simple tools for the design of shallow foundations (i.e., footings) in sands under both static and dynamic loading conditions.
Terzaghi (1943) or Meyerhof (1951) equations for bearing capacity and Schmertmann et al. (1978) equation for settlement are routinely used by practicing engineers for sandy soils based on saturated soil properties. The assumption of saturated conditions leads to conservative estimates for bearing capacity; however, neglecting the influence of capillary stresses contributes to unreliable estimates of settlement or differential settlement of footings in unsaturated sands. There are no studies reported in the literature on how capillary stresses influence liquefaction, bearing capacity and settlement behavior in earthquake prone regions under dynamic loading conditions. An extensive experimental program has been undertaken to study these parameters using several specially designed and constructed equipment at the University of Ottawa.
The influence of matric suction, confinement and dilation on the bearing capacity of model footings in unsaturated sand was determined using the University of Ottawa Bearing Capacity Equipment (UOBCE-2011). Several series of plate load tests (PLTs) were carried out on a sandy soil both under saturated and unsaturated conditions. Based on these studies, a semi-empirical equation has been proposed for estimating the variation of bearing capacity with respect to matric suction. The saturated shear strength parameters and the soil water characteristic curve (SWCC) are required for using the proposed equation. This equation is consistent with the bearing capacity equation originally proposed by Terzaghi (1943) and later extended by Meyerhof (1951) for saturated soils. Chapter 2 provides the details of these studies.
The cone penetration test (CPT) is conventionally used for estimating the bearing capacity of foundations because it is simple and quick, while providing continuous records with depth. In this research program, a cone penetrometer was specially designed to investigate the influence of matric suction on the cone resistance in a controlled laboratory environment. Several series of CPTs were conducted in sand under both saturated and unsaturated conditions. Simple correlations were proposed from CPTs data to relate the bearing capacity of shallow foundations to cone resistance in saturated and unsaturated sands. The details of these studies are presented and summarized in Chapter 3.
Standard penetration tests (SPTs) and PLTs were conducted in-situ sand deposit at Carp region in Ottawa under both saturated and unsaturated conditions. The test results from the SPTs and PLTs at Carp were used along with other data from the literature for developing correlations for estimating the bearing capacity of both saturated and unsaturated sands. The proposed SPT-CPT-based technique is simple and reliable for estimation of the bearing capacity of footings in sands. Chapter 4 summarizes the details of these investigations.
Empirical relationships were proposed using the CPTs data to estimate the modulus of elasticity of sands for settlement estimation of footings in both saturated and unsaturated sands. This was achieved by modifying the Schmertmann et al. (1978) equation, which is conventionally used for settlement estimations in practice. Comparisons are provided between the three CPT-based methods that are commonly used for settlement estimations in practice and the proposed method for seven large scale footings in sandy soils. The results of the comparisons show that the proposed method provides better estimations for both saturated and unsaturated sands. Chapter 5 summarizes the details of these studies.
A Flexible Laminar Shear Box (FLSB of 800-mm3 in size) was specially designed and constructed to simulate and better understand the behaviour of model surface footing under seismic loads taking account of the influence of matric suction in an unsaturated sandy soil. The main purpose of using the FLSB is to simulate realistic in-situ soils behaviour during earthquake ground shaking. The FLSB test setup with model footing was placed on unidirectional 1-g shake table (aluminum platform of 1000-mm2 in size) during testing. The resistance of unsaturated sand to deformations and liquefaction under seismic loads was investigated. The results of the study show that matric suction offers significant resistance to liquefaction and settlement of footings in sand. Details of the equipment setup, test procedure and results of this study are presented in Chapter 6.
Simple techniques are provided in this thesis for estimating the bearing capacity and settlement behaviour of sandy soils taking account of the influence of capillary stresses (i.e., matric suction). These techniques are consistent with the methods used in conventional geotechnical engineering practice. The studies show that even low values of capillary stresses (i.e., 0 to 5 kPa) increases the bearing capacity by two to four folds, and the settlement of footings not only decreases significantly but also offers resistance to liquefaction in sands. These studies are promising and encouraging to use ground improvement techniques; such as capillary barrier techniques to maintain capillary stresses within the zone of influence below shallow foundations. Such techniques, not only contribute to the increase of bearing capacity, they reduce settlement and alleviate problems associated with earthquake effects in sandy soils.
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Russi, Daniel. "ESTUDO DO COMPORTAMENTO DE SOLOS ATRAVÉS DE ENSAIOS DE PLACA DE DIFERENTES DIÂMETROS." Universidade Federal de Santa Maria, 2007. http://repositorio.ufsm.br/handle/1/7667.
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The dimensioning of shallow foundations requires the professional to define clearly and objectively, for the soil in question, the load capacity and forecast the settlings of the foundation submitted to the structure having as base its mechanical properties obtained through field and/or laboratory investigation. One of the safest ways to take this decision is based on information from plate load tests because through this it is possible to reproduce in a minor proportion the real behavior of the future foundation, perhaps using this as a tool to help in the decision making to dimension shallow foundations, contributing to a more efficient development of the foundation work. The present work is about the analysis of the CEEG/UFSM soil behavior through tests on direct load proof on foundation field (plate load test). The research is divided, basically into two great phases. There was an experimental phase which comprehended geotechnical characterization trials and plate load tests to evaluate
the behavior tension-settling of foundation. There were 7 plate load tests in 3 ditches dug manually up to 0,7 m depth. Plates with 15, 30 and 50 cm diameter were used and the reaction system was formed by reaction piles united by a reaction beam. The second phase was the analysis of the results obtained, analyzed through curves tension-settling of foundation, where some criteria were applied to define the rupture tension and some considerations were done on the settling of foundation forecast and scale effect.O dimensionamento de fundações superficiais requer que o profissional defina de forma clara e objetiva, para o solo em questão, a capacidade de carga e a previsão dos recalques que se submete à estrutura, baseando-se em suas propriedades mecânicas obtidas em investigações de campo e/ou laboratório. Uma das formas mais seguras de se tomar essa decisão está baseada nas informações advindas do ensaio de carregamento direto sobre placas, pois, através dele, se reproduz em escala reduzida o comportamento real da futura fundação, podendo servir como ferramenta de auxílio na tomada de decisão para o dimensionamento de fundações superficiais, contribuindo para o desenvolvimento mais eficaz das obras de fundação. O presente trabalho trata da análise do comportamento do solo do CEEG/UFSM através do ensaio de prova de carga direta sobre terreno de fundação (ensaio de placa). A pesquisa dividiu-se basicamente em duas grandes etapas. Uma etapa experimental, a qual compreendeu ensaios de caracterização geotécnica e ensaios de placa para a avaliação do comportamento tensão-recalque. Realizou-se 7 ensaios de placa em três trincheiras escavadas manualmente até a profundidade de 0,7 metros. Utilizou-se placas de 15, 30 e 50 cm de diâmetro e o sistema de reação compreendia estacas de reação unidas por uma viga de reação. A segunda etapa consistiu na análise dos resultados obtidos, analisados através de curvas tensão-recalque, as quais se aplicaram alguns critérios para definir a tensão de ruptura e fez-se algumas considerações sobre a previsão de recalques e o efeito escala.
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Foppa, Diego. "Novo método para cálculo da capacidade de carga de fundações superficiais assentes sobre camada de reforço em solo cimento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/156817.
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Pesquisas recentes têm mostrado que a utilização de camada de reforço em solo-cimento é uma alternativa para o aumento da capacidade de carga e redução dos recalques de fundações superficiais em solos de baixa resistência. Os métodos para previsão da capacidade de carga em sistemas de dupla camada encontrados na literatura trazem implícita a premissa de que a camada superior é contínua ou suficientemente maior que a largura da fundação. O objetivo desta pesquisa foi desenvolver um novo método para o cálculo de capacidade de carga de fundações superficiais assentes sobre uma camada de reforço em solo-cimento, considerando sua extensão lateral. Para tanto, foram realizados ensaios em modelos reduzidos de fundações contínuas assentes sobre um solo arenoso fofo, bem como, análises numéricas através do método dos elementos finitos. Observaram-se dois tipos distintos de ruptura. No primeiro, a camada de reforço é puncionada para dentro do solo natural, sem apresentar fissuras, até o deslocamento correspondente à capacidade de carga do solo natural No segundo, após um recalque inicial, a camada de reforço rompe com o aparecimento de uma fissura, que pode localizar-se junto à borda ou no eixo da fundação, e se propaga de baixo para cima, à medida que aumentam os recalques. Verificou-se que a máxima tensão de tração na camada de reforço é função da reação do solo na base do reforço e da relação Tr/Hr, onde Tr é a distância horizontal entre a borda da fundação e a borda do reforço e Hr é a espessura do reforço. A partir destas observações, foi desenvolvido um novo método de cálculo com a premissa de que a ruptura ocorra no solo e não na camada de reforço. Assim, é possível calcular a capacidade de carga considerando que fundação e reforço atuam como um elemento único, apoiado na mesma profundidade de assentamento do reforço. Ao mesmo tempo, é apresentada uma equação para previsão da máxima tensão de tração que atuará no reforço, a partir da qual, se pode dimensioná-lo com segurança.Recent researches have shown that the use of soil-cement reinforcement layer is an alternative to increase bearing capacity and reduce settlements of shallow foundations in low resistance soils. The existing methods for predicting bearing capacity of double layer systems implicitly assume that the top layer is continuous or sufficiently greater than the foundation width. This study aims to develop a new method for bearing capacity calculation of shallow foundations supported by a soil-cement reinforcing layer, considering its lateral extension. Therefore, small scale tests of continuous foundations on a loose sandy soil, as well as, numerical analysis by the finite element method were carried out. It was observed two distinct types of failure. In the first, the reinforcement layer is punched through the sandy soil, without showing any cracking, up to a settlement which corresponds to the sand bearing capacity. In the second, after an initial settlement, the reinforcement layer breaks up, showing a fissure, which may be located near the edge or the axis of foundation, and propagates upward as the settlements continues. It was found that the maximum tensile stress in the reinforcement layer is a function of soil reaction on the reinforcement and the ratio Tr/Hr, where Tr is the horizontal distance between the edge of the foundation and the edge soil-cement layer and Hr is the thickness of the soil-cement layer. From these observations, it was developed a new calculation method, with the assumption that the failure occurs in the soil and not in the reinforcement layer. Thus, it is possible to calculate the bearing capacity considering that foundation and reinforcement act as a single element, supported at the same depth of the reinforcement base. In order to design the soil-cement layer, an equation for the maximum tensile stress prediction is provided.
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Antoniazzi, Juliana Pippi. "INTERAÇÃO SOLO-ESTRUTURA DE EDIFÍCIOS COM FUNDAÇÕES SUPERFICIAIS." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/7763.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis work deals with the consideration of Soil-Structure Interaction (SSI) in structural design of reinforced concrete buildings on shallow foundations of the isolated footing type. It carried out a comprehensive review on the major works done in the area and the methods for obtaining parameters and variables involved in the analysis. Numerical examples were developed with the aim of identifying internal forces and displacements changes caused by considering the deformation of soil and the construction sequence in the structural analysis. The examples also intended to show data and procedures for the required calculations in the consideration of the SSI in structural designs. Among the computational tools used in the numerical examples is ESPACIAL_ISE program - a program developed in FORTRAN by Alva (2010). This program employs the method of Aoki and Lopes (1975), which uses the equations of Mindlin (1936) for calculating the settlements, together with the Steinbrenner´s method (1934) to consider the stratigraphy of the soil mass. It was also used in the numerical examples SISEs computer system (System of Soil-Structure Interaction) - developed by TQS Informatics - which allows that the entire structure and foundation are represented in a single structural model. The results of this study showed the importance of considering the soil deformation, although in a simplified form, replacing the fixed support hypothesis in structural designs. Thus, for a more realistic structural analysis of multistory buildings, it is recommended that the soil-structure interaction is considered together with the construction sequence.
O presente trabalho trata da consideração da Interação Solo-Estrutura (ISE) em projetos estruturais de edifícios em concreto armado sobre fundações superficiais do tipo sapatas isoladas. É realizada uma ampla revisão bibliográfica sobre os principais trabalhos desenvolvidos na área e sobre os métodos para a obtenção de parâmetros e variáveis envolvidos na análise. Exemplos numéricos foram desenvolvidos com o intuito de identificar as alterações de esforços e deslocamentos ocasionadas ao se considerar a deformabilidade do solo e a sequência construtiva na análise estrutural. Os exemplos também tiveram como objetivo mostrar os dados e os procedimentos de cálculo necessários para a consideração da ISE em projetos estruturais. Entre as ferramentas computacionais utilizadas nos exemplos numéricos está o programa ESPACIAL_ISE - programa desenvolvido em linguagem FORTRAN por Alva (2010). O referido programa emprega o método de Aoki e Lopes (1975), o qual utiliza as equações de Mindlin (1936) para o cálculo dos recalques, em conjunto com o procedimento de Steinbrenner (1934) para considerar a estratigrafia do maciço de solos. Também foi utilizado nos exemplos numéricos o sistema computacional SISEs (Sistema de Interação Solo-Estrutura) desenvolvido pela TQS Informática - o qual permite que toda a estrutura e a fundação sejam representadas em um modelo estrutural único. Os resultados obtidos neste trabalho mostraram a importância da consideração da deformabilidade do solo, ainda que de forma simplificada, em substituição à hipótese de apoios indeslocáveis nos projetos estruturais. Para uma análise estrutural mais realista em edifícios de múltiplos andares, recomenda-se que a interação solo-estrutura seja considerada juntamente com a sequência construtiva.
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Júnior, Osvaldo Gomes de Holanda. "Interação solo-estrutura para edifícios de concreto armado sobre fundações diretas." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-21122017-114906/.
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Interação solo-estrutura é o objeto de estudo deste trabalho. O principal objetivo é verificar a verdadeira importância desse fenômeno na análise estrutural de edifícios usuais em concreto armado sobre fundações diretas. Inicialmente apresenta-se um estudo sobre o comportamento do solo. Logo após são descritos os processos de dimensionamento de fundações superficiais, com base na NBR 6122 (1996). Descrevem-se em seguida os elementos barra e sapata rígida, utilizados na modelagem do sistema superestrutura-subestrutura-maciço de solos. Discute-se a modificação do elemento sapata rígida, que representa fundação e solo, para a consideração de uma camada indeslocável no interior do solo. De acordo com a teoria apresentada, dois exemplos são submetidos a duas análises, com ou sem a consideração da interação sol-estrutura, para que os resultados sejam comparados. Aplicam-se separadamente as ações verticais e horizontais. A influência duma camada indeslocável no interior do solo e os efeitos da seqüência construtiva dos edifícios também são analisados.Soil-structure interaction is the subject of this work. The foremost aim is to verify the real importance of that phenomenon on the structural analysis of usual reinforced concrete buildings on shallow foundations. At first, it is presented a study of soil behaviour. Design procedures of shallow foundations based on NBR 6122 (1996) are described afterwards. Then, the beam and rigid footing elements, used for modelling the superstructure-infrastructure-foundation soil system, are described. It is discussed the modification of the rigid footing element, which represents foundation and soil, to consider a rigid layer within soil. According to the theory above presented, two examples are subjected to two analysis, with or without the consideration of soil-structure interaction, in order to compare the results. Vertical and horizontal loads are separately applied. The influence of a rigid layer within soil and the effects of the sequence of buildings construction are also analysed.
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Raja, Muhammad Nouman Amjad. "Load-settlement investigation of geosynthetic-reinforced soil using experimental, analytical, and intelligent modelling techniques." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2455.
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During the past five decades, numerous studies have been conducted to investigate the load-settlement behaviour of geosynthetic-reinforced soil. The main advantage of reinforced soil foundations are the increase in the bearing capacity and decrease in the settlement. Whereas, for pavement foundation design, the strength of the subgrade soil is often measured in terms of California bearing ratio (CBR). The researchers have suggested various methods to improve the quality of geosynthetic-reinforced foundations soils. In the recent past, the wraparound geosynthetic reinforcement technique has been proposed to strengthen the foundation soil effectively. However, there are several research gaps in the area; for example, there has been no analytical solution for estimating the ultimate bearing capacity of wraparound reinforced foundations, and there has been no evaluation of this technique under repeated loading conditions. Similarly, for planar geosynthetic-reinforced soil foundations, the prediction of load-settlement behaviour also requires more attention. The advent of artificial intelligence (AI) based modelling techniques has made many traditional approaches antiquated. Despite this, there is limited research on using AI techniques to derive mathematical expressions for predicting the load-settlement behaviour of reinforced soil foundations or the strength of reinforced subgrade soil.
This research is undertaken to examine the load-settlement behaviour of geosynthetic-reinforced foundation soils using experimental, analytical, and intelligent modelling methods. For this purpose, extensive laboratory measurements, analytical, numerical and AI-based modelling and analysis have been conducted to: (i) derive theoretical expression to estimate the ultimate bearing capacity of footing resting on soil bed strengthened by wraparound reinforcement technique; (ii) using detail experimental study, present the effectiveness of wraparound reinforcement for improving the load-settlement characteristics of sandy soil under repeated loading conditions; (iii) to build the executable artificial intelligence-based or computationally intelligent soft computing models and converting them into simple mathematical equations for estimating the (a) ultimate bearing capacity of reinforced soil foundations; (b) settlement at peak footing loads; (c) strength (California bearing ratio) of geosynthetic-reinforced subgrade soil; and (iv) to examine and predict the settlement of geosynthetic-reinforced soil foundations (GRSF) under service loading condition using novel hybrid approach, that is, finite element modelling (FEM) and AI modelling.
In the analytical phase, a theoretical expression has been developed for estimating the ultimate bearing capacity of strip footing resting on soil bed reinforced with the geosynthetic layer having the wraparound ends. The wraparound ends of the geosynthetic reinforcement are considered to provide the shearing resistance at the soil-geosynthetic interface as well as the passive resistance due to confinement of soil by the geosynthetic reinforcement. The values of ultimate load-bearing capacity determined by using the developed analytical expression have predicted values closer to the model studies reported in the literature, with a difference in the range of 0% to 25% with an average difference of 10%.
In the experimental phase, model footing load tests have been conducted on strip footing resting on a sandy soil bed reinforced with geosynthetic in wraparound and planar forms under monotonic and repeated loadings. The geosynthetic layers were laid according to the reinforcement ratio to minimise the scale effect. The effect of repeated load amplitude and the number of cycles, and the effect of reinforcement parameters, such as number of layers, reinforcement width, lap-length ratio and planar width of wraparound, were investigated, and their potential effect on the load-settlement behaviour has been studied. The wraparound reinforced model has shown about 45% lower average total settlement than the unreinforced model. In comparison, the double-layer reinforced model has about 41% at the cost of twice the material and 1.5 times the occupied land width ratio. Additionally, for lower settlement levels (s/B ≤ 5%), the wraparound geotextile with a smaller occupied land width ratio (bp/B = 3.5) has performed well in comparison to the wraparound with a slightly larger occupied land width ratio (bp/B = 4). However, the wraparound with occupied width ratio of 4 provides more stability to the foundation soil for higher settlement levels. The performance of the fully wrapped model (bp/B = 2.8) is more similar to that of the planar double-layer reinforced model (b/B = 4); however, it is noted that even the fully wrapped model outperforms the planar single-layer reinforced model with the same amount of geotextile and 50% less occupied land width
For data analytic methods, first historical data has been collected to build the various machine learning (ML) models, and then detailed comparison has been presented among the ML-based models and with other available theoretical methods. A comprehensive study was conducted for each model to choose its structure, optimisation, and tuning of hyperparameters and its interpretation in the form of mathematical expressions. The forecasting strength of the models was assessed through a cross-validation approach, rigorous statistical testing, multi-criteria approach, and external validation process. The traditional statistical indices such as coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percent deviation (MAPD); along with several other modern model performance indicators, were utilised to evaluate the accuracy of the developed models. For ultimate bearing capacity (UBC) estimation, the performance of the extreme learning machine (ELM) and TreeNet models has shown a good degree of prediction accuracy in comparison with traditional methods over the test dataset. However, the overall performance of the ELM model (R2 = 0.9586, MAPD=12.8%) was better than that of the TreeNet model (R2 = 0.9147, MAPD =17.2%). Similarly, for settlement estimation at peak footing loads, multivariate adaptive regression splines (MARS) modelling technique has outperformed (R2 = 0.974, RMSE = 1.19 mm, and MAPD = 7.19%) several other robust AI-based models, namely ELM, support vector regression (SVR), Gaussian process regression (GPR), and stochastic gradient boosting trees (SGBT). For CBR, the competency and reliability of the several intelligent models such as artificial neural network (ANN), least median of squares regression (LMSR), GPR, elastic net regularization regression (ENRR), lazy K-star (LKS), M5 model trees, alternating model trees (AMT), and random forest (RF). Among all the intelligent modelling techniques, ANN (R2 = 0.944, RMSE = 1.74, and MAE = 1.27) and LKS (R2 = 0.955, RMSE = 1.52, and MAE = 1.04) has achieved the highest ranking score of 35 and 40, respectively, in predicting the CBR of geosynthetic-reinforced soil. Moreover, for UBC and settlement at peak footing loads, new model footing load tests, and for strength of reinforced subgrade soil, new CBR tests were also conducted to verify the predictive veracity of the developed AI-based models.
For predicting the settlement behaviour of GRSF under various service loads, an integrated numerical-artificial intelligence approach was utilised. First, the large-scale footing load tests were simulated using the FEM technique. At the second stage, a detailed parametric study was conducted to find the effect of footing-, geosynthetic- and soil strength- parameters on the settlement of GRSF under various service loads. Afterward, a novel evolutionary artificial intelligence model, that is, grey-wolf optimised artificial neural network (ANN-GWO), was developed and translated to the simple mathematical equation for estimating the load-settlement behaviour of GRSF. The results of this study indicate that the proposed ANN-GWO model predict the settlement of GRSF with high accuracy for training (RMSE = 0.472 mm, MAE = 0.833, R2 = 0.982), and testing (RMSE = 0.612 mm, MAE = 0.363, R2 = 0.962,) dataset. Furthermore, the predictive veracity of the model was verified by detailed and rigorous statistical testing and against several independent scientific studies as reported in the literature.
This work is practically valuable for understanding and predicting the load-settlement behaviour of reinforced soil foundations and applies to traditional planar geosynthetic-reinforced and as well as recently developed wraparound geosynthetic-reinforced foundation soil technique. For wraparound reinforced soil foundations, the analytical expression will be helpful in the estimation of ultimate bearing capacity, and experimental study shows the beneficial effects of such foundations systems in terms of enhancement in bearing capacity and reduction in the settlement, and economic benefits in terms of saving land area and amount of geosynthetic, under repeated loading conditions. Moreover, the developed AI-based models and mathematical expressions will be helpful for the practitioners in predicting the strength and settlement of reinforced soil in an effective and intelligent way and will be beneficial in the broader understanding of embedding the intelligent modelling techniques with geosynthetic-reinforced soil (GRS) technology for the automation in construction projects.
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Vianna, Ana Paula Fontana. "Influência da dimensão e da sucção matricial no comportamento de fundações superficiais assentes em solo arenoso não-saturado." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-28042006-100500/.
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Analisa-se a influência da sucção matricial e da dimensão de sapatas na capacidade de carga e nos recalques de fundações rasas, assentes em areia não-saturada. Na primeira parte da pesquisa foram analisadas 14 provas de carga estática em placas metálicas rígidas assentes a 1,5 m de profundidade, com diâmetros de 0,20, 0,40 e 0,80m e em uma sapata circular de concreto com diâmetro de 1,50 m, no campo experimental de fundações da USP/São Carlos. Devido ao caráter colapsível do solo, a sucção matricial foi monitorada por meio de tensiômetros instalados no fundo da cava. Na segunda parte da pesquisa, foram realizados ensaios em centrífuga, na Universidade do Colorado em Boulder, utilizando-se placas metálicas de 30 mm, 50 mm e 100 mm, ensaiadas a 1 g, 5 g, 10 g, 15 g, 25 g, 50 g e 100 g. As placas foram assentes em maciço de areia em três condições de umidade: seca, inundada e não-inundada. A partir dos resultados obtidos, procedeu-se a análise da capacidade de carga levando-se em conta tanto o efeito da dimensão como o da sucção matricial. A influência da dimensão nos recalques também foi analisada. Ratificou-se que o aumento da sução matricial provoca um aumento substancial na capacidade de carga do sistema placa-solo e uma diminuição considerável nos recalques. Em relação à influência da dimensão no comportamento de fundações rasas, demonstrou-se que tanto a variação da capacidade de carga como a dos recalques não ocorre de forma linear e crescente como apresentado pelos métodos teóricos. Para pequenas dimensões da sapata, os valores de capacidade de carga e recalque aumentamThe influence of matric suction and size of footings in the bearing capacity and settlement of shallow foundations in unsaturated sandy soils are analyzed. Fourteen plate load tests were performed in the first part of the research. Rigid metallic plates with diameters 0,20, 0,40, 0,80 m and one concrete circular footing with 1,50 m were used in the tests. All plates and footing were positioned at 1,50 m depth. The tests were performed in the foundation experimental field of USP/São Carlos. Due to the soil collapsible character, the tests were performed with the monitoring of matric suction pressure through tensiometers installed in the bottom of the holes. Centrifuge tests were carried out at the University of Colorado at Boulder in the second part of the research. Metallic plates with 30 mm, 50 mm and 10 mm were used and the gravity levels were 1 g, 5 g, 10 g, 15 g, 25 g, 50 g e 100 g. The plates were positioned on top of a sandy soil with three moisture conditions: dry, flooded and non-flooded. Thus, the capacity will be analyzed taking into consideration both the geometry of the tested plates and the influence of the matric suction pressure. The footing size influence in the settlement was also analyzed. A substantial increase of the plate-soil system bearing capacity and a considerable decrease in the settlements, caused by matric suction increase, was confirmed. It was also demonstrated that the bearing capacity and settlements variations are not a linearly increasing function of the size as theoretical methods suggest. For small footings, the bearing capacity and settlement increase as the footing size decreases
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RIBEIRO, ROMULO CASTELLO HENRIQUES. "CONFIABILITY AND PROBABILITY IN GEOTECHNICS OF SHALLOW FOUNDATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2000. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1779@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO interesse por análises de confiabilidade em geotecnia tem aumentado muito nos últimos anos. Métodos probabilísticos tem sido utilizados com o objetivo de racionalizar a quantificação das incertezas existentes na geotecnia. Neste âmbito, o presente trabalho apresenta um resumo com os conceitos básicos de probabilidade necessários para a compreensão do assunto. Desenvolve-se o Método do Segundo Momento de Primeira Ordem para quantificação da confiabilidade inerente ao desempenho de fundações. Metodologias são propostas para racionalizar a adoção de fatores de segurança quanto à ruptura de fundações superficiais e quantificar o risco associado à probabilidade do recalque estimado ser superior ao recalque admissível. Os exemplos de cálculo são apresentados com base no desempenho de fundações protótipo submetidas a provas de carga superficiais executadas no campo experimental 1 da PUC-Rio.
The interest for reliability analysis in geotechnical engineering has been growing up in the last two decades. Probabilistic methods are generally used as a way of rationalizing the analysis of the uncertainties presents in the geotechnical properties. The First Order Second Moment method (FOSM) was applied in order to quantify the reliability of foundations. A methodology is proposed for quantifying the probability of faylure of shallow foundations and also the probability of settlements larger than the allowable design value. Example calculations are presented with basis on the results of prototype footings tested in the experimental research site at PUC-Rio.
EL interés por análisis de confiabilidad en geotecnia ha aumentado mucho en los últimos años. Métodos probabilísticos han sido utilizados con el objetivo de racionalizar la cuantificación de las incertezas que existen en la geotecnia. En este ámbito, el presente trabajo presenta un resumen de los conceptos básicos de las probabilidades, necesarios para la comprensión del asunto. Se desarrolla el Método del Segundo Momento de Primer Orden para cuantificar la confiabilidad inherente al desempeño de fundaciones. Se proponen metodologías para racionalizar la adopción de factores de seguridad y cuantificar el riesgo asociado a la probabilidad de que el recalco estimado sea superior al recalco admisible. Los ejemplos de cálculo presentados tienen como base el desempeño de fundaciones prototipos, sometidas a pruebas de carga superficiales, ejecutadas en el campo experimental 1 de la PUC-Rio.
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Burnier, Andréia Aparecida Lopes. "Análise numérica de provas de carga em sapatas utilizando o método dos elementos finitos." Universidade Federal de Viçosa, 2006. http://locus.ufv.br/handle/123456789/3740.
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This work presents numerical analyses of shallow foundations. Two load tests performed by GOUVÊA (2000) and DUARTE (2006) were analyzed using the finite element method. The stress-strain behavior of the soils was represented by different constitutive models: a non-linear-elastic (hyperbolic), an elastic-perfectly-plastic (Mohr-Coulomb) and an elastoplastic (Lade-Kim). The constitutive model parameters were determined from triaxial and oedometer tests. Results of these analyses were compared to the load-settlement curves obtained from the field tests. The main conclusions are that the numerical solution obtained using the hyperbolic model provided the best comparisons with the test performed by DUARTE (2006) and the solution obtained using the Mohr-Coulomb model supplied the best comparisons with the test accomplished by GOUVÊA (2000). Also, the stress bulbs obtained from numerical analyses were deeper than the ones normally considered in practical situations. Finally, the numerical analyses confirmed the local failure observed on the field tests.
Nesse trabalho apresentam-se as análises numéricas de duas provas de carga instrumentadas realizadas em fundações superficiais rígidas (sapatas) por GOUVÊA (2000) e DUARTE (2006). As análises foram realizadas com o método dos elementos finitos, utilizando os programas SIGMA/W da Geo-Slope International Ltd. e ANLOG (Análise Não-Linear de Obras Geotécnicas) desenvolvido por NOGUEIRA (1998). Na modelagem do comportamento tensão-deformação do solo foram utilizados os modelos constitutivos linear e elástico, não-linear e elástico (hiperbólico), o modelo elástico-perfeitamente-plástico de Mohr-Coulomb e o modelo elasto-plástico de Lade-Kim. Os parâmetros utilizados em cada um desses modelos foram obtidos através de ensaios triaxiais e edométricos realizados por GOUVÊA (2000) e DUARTE (2006). Os resultados dessas análises foram comparados com os resultados experimentais, medidos nas provas de carga. As principais conclusões foram que o modelo hiperbólico forneceu as melhores comparações para a análise com os dados de DUARTE (2006) e para os dados de GOUVÊA (2000) o modelo de Mohr-Coulomb obteve uma melhor representatividade da curva de tensão-recalque até a tensão de 310 kPa; o programa ANLOG teve um desempenho melhor que o do programa SIGMA/W; os bulbos de tensão obtidos nas análises numéricas foram mais profundos dos que os normalmente considerados em situações práticas e as análises numéricas confirmaram a ruptura por puncionamento observada nos ensaios de campo.
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Chen, Yung-Chieh. "Seismic bearing capacity of shallow and deep strip foundation." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8665.
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Souza, Tiago de Jesus. "Previsão da curva tensão-recalque em solos tropicais arenosos a partir de ensaios de cone sísmico." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-25042012-163755/.
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Apresenta-se neste trabalho a aplicação de um método para a previsão da curva tensão-recalque de fundações diretas assentes em solos tropicais arenosos a partir de resultados de ensaios de cone sísmico (SCPT). Os locais estudados foram os campos experimentais de fundações da EESC/USP - São Carlos e da UNESP-Bauru, onde existem resultados de provas de carga realizados a diferentes profundidades, assim como resultados de ensaios SCPT. As previsões realizadas apresentaram bons resultados, após ajustes dos parâmetros f e g, pois as curvas tensão-recalque estimadas foram próximas a aquelas obtidas a partir de provas de carga em placa, para as profundidades maiores que 1,5 metros. Verifica-se assim a aplicabilidade do método, após seu ajuste, para reproduzir a curva tensão-recalque neste tipo de solo, empregando uma abordagem mais racional, com menor dependência de correlações empíricas. Destaca-se nesta pesquisa que existe uma variabilidade dos resultados de ensaios SCPT e de provas de carga que está relacionada com a mudança de sucção no solo. Para o campo experimental de São Carlos foi possível ainda fazer uma avaliação da variabilidade nas previsões realizadas, pois existe maior número de resultados de ensaios de campo e provas de cargas disponíveis.It is presented in this dissertation the use of a method for predicting the stress-settlement curve of shallow foundations on tropical sandy soils based on seismic cone (SCPT) test results. The studied sites were the experimental research sites from USP - São Carlos, and UNESP - Bauru, Brazil, where there are results from plate load tests conducted at various depths, as well as SCPT test results. The stress-settlement curve predictions show good results, after adjusting the parameters f and g, because the estimated curves were close to those obtained from plate load tests, to depths greater than 1.5 meters. The applicability of the method, after its adjustment, to reproduce the stress-settlement curve for this type of soil, was verified employing a more rational approach with less reliance on empirical correlations. It is highlighted in this research that there is variability on SCPT and plate load test results, which is related to the change in soil suction. It was also possible to access the variability on the prediction for the USP São Carlos site, since there is a greater number of in situ and plate load tests in this site.
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Lebegue, Yves. "Fondations superficielles sur milieu homogène horizontal ou incliné et sur milieu hétérogène sable sur argile molle." Poitiers, 1987. http://www.theses.fr/1987POIT2023.
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Dans la 1ere partie, etude theorique et experimentale (semelles de 6 et 20 cm dans du sable de loire) du comportement de semelles sur milieu homogene incline et avec charge inclinee (les contraintes de rupture sont superieures aux valeurs theoriques). Dans la 2eme partie, etude experimentale de semelles filantes, carrees et circulaires, poinconnant des couches de sable atteignant 2 fois la largeur de la fondation, et reposant sur de la graisse ou de la vase
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Ferrando, Sanchez Abel Junior, and Valdez Marcelo Eduardo Himuro. "Comparación de la probabilidad de falla y el factor de seguridad aplicado en el diseño de zapatas aisladas aplicadas a edificaciones inmobiliarias de Lima utilizando métodos probabilísticos basados en el coeficiente de confiabilidad y el método de Monte Carlo." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/654545.
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Se presenta la propuesta de un factor probabilístico para determinar el porcentaje de falla que se puede presentar en cimentaciones superficiales, en nuestro caso zapatas. En este articulo presentaremos una comparación entre el factor de seguridad (F.S), definido por la norma E050 Suelos y Cimentaciones, y la probabilidad de falla. Este método se ejecutará a través de la simulación de datos de entrada, tales como peso específico, cohesión, ángulo de fricción y solicitación de carga. Para este proceso de simulación se aplicará el método Monte Carlo. Una vez obtenido los valores de la resistencia del suelo, teniendo en cuenta su distribución normal, y la solicitación, se comenzará a analizar las probabilidades de fallar mediante las curvas de densidad de la resistencia y solicitación. Finalmente analizaremos la relación que se dará entre el F.S y la probabilidad de falla para observar su comportamiento al aumentar los parámetros para la resistencia.The proposal of a probabilistic factor is presented to determine the percentage of failure that can occur in shallow foundations, in our case footings. In this article we will present a comparison between the safety factor (F.S), defined by the standard E050 Soils and Foundations, and the probability of failure. This method will be executed through the simulation of input data, such as specific weight, cohesion, angle of friction and load stress. For this simulation process, the Monte Carlo method will be applied. Once the soil resistance values have been obtained, considering its normal distribution and the stress, the probabilities of failure will begin to be analyzed using the strength and stress density curves. Finally, we will analyze the relationship that will occur between the F.S and the probability of failure to observe the behavior when increasing the parameters for resistance.
Trabajo de investigación