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Kim, Jong Hee. "Improvement of geotechnical site investigations via statistical analyses and simulation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41218.
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The purpose of this study is to improve site investigation in geotechnical engineering via the evaluation and development of statistical approaches for characterizing the spatial variability of soil properties and the development of site investigation simulation software for educational use.
This study consists of four components: statistical characteristics, data measurement, simulation, and educational training. Statistical measures of spatial variability of soil properties were examined for three different geographical areas where soil formation processes differ to assess the influence on the spatial variability of soils. Statistical measures of spatial variability were also calculated for a case history where blasting was used as a method of soil improvement to evaluate the effects of man-made changes to soil structure.
The concept of spatial aliasing was employed to estimate the maximum allowable sampling interval for field data as a function of the spatial correlation properties. Once a maximum statistically allowable sampling interval is determined for a specific soil property, the minimum statistically required number of soundings / borings is calculated to perform an economical site investigation at a specific site.
A simple and efficient simulation technique was proposed to generate correlated, multi-dimensional simulations of soil properties. Based on limited data, the proposed simulation technique generated accurate and correlated simulations of soil properties that are consistent with the observed or proposed correlation structures of soil properties.
Lastly, a geotechnical site investigation simulation program with a wide variety of in situ and laboratory tests was developed to allow students to plan and perform a comprehensive site investigation program. The simulation generates an input file based partly on the statistical characteristics of the spatial variability of soil properties analyzed in this study and partly on traditional values. Spatial variability in soil properties is modeled via correlated random fields, interpolation, and a decomposition method to yield realistic geotechnical data. Via the simulation, students are able to obtain experience and judgment in an essential component of geotechnical engineering practice.
The four components of this research (statistical characteristics, data measurement, simulation, and educational training) focus on the improvement of site investigation performance in geotechnical engineering, thereby improving reliability analysis in geotechnical practice.
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Arque, Armengol Anna. "Comparison between preinvestigations and detailed geotechnical site characterization of City Link, Stockholm." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171800.
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A statistical comparison between the pre-investigations and the detailed site characterization while tunneling was performed in three areas of different rock quality in the Södermalm’s Tunnel. An overview of the site investigations performed prior to the construction works and the consequences in the tunneling method are also presented in this study. The statistical analyses in this study showed low correlation within the results obtained from the geotechnical investigations performed prior and while tunneling. The correlation diminishes as the rock mass quality decreases; however, in areas where the rock mass quality is high, the correlation is not as elevated as expected. The low association within those results may be due to diverse factors: the concentration of the pre-investigations in mostly three areas along the trace of the tunnel, and the extension of those results to the rest of the tunnel; the inappropriate utilization of the investigation techniques; and the lack of geotechnical data in the regional areas of Stockholm. The inaccurate geological characterization given by the pre-investigations leaded to great challenges in the most fractured and altered areas of the tunnel. A collapse occurred where the glaciofluvial sediments were in contact with the rock. The excavation had to be stopped and additional rock reinforcement had to be applied. Therefore, an increase of the expenses in terms of time and budget were the major consequences of the inaccurate predictions.
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Prästings, Anders. "Aspects on probabilistic approach to design : From uncertainties in pre-investigation to final design." Licentiate thesis, KTH, Jord- och bergmekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-178088.
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Geotechnical engineering is strongly associated with large uncertainties. Exploring a medium (soil) that is almost entirely and completely hidden from us is no easy task. Investigations can be made only at discrete points, and the majority of a specific soil volume is never tested. All soils experience inherent spatial variability, which contributes to some uncertainty in the design process of a geotechnical structure. Furthermore, uncertainties also arise during testing and when design properties are inferred from these tests. To master the art of making decisions in the presence of uncertainties, probabilistic description of soil properties and reliability-based design play vital roles. Historically, the observational method (sometimes referred to as the “learn-as-you-go-approach”), sprung from ideas by Karl Terzaghi and later formulated by Ralph Peck, has been used in projects where the uncertainties are large and difficult to assess. The design approach is still highly suitable for numerous situations and is defined in Eurocode 7 for geotechnical design. In paper I, the Eurocode definition of the observational method is discussed. This paper concluded that further work in the probabilistic description of soil properties is highly needed, and, by extension, reliability-based design should be used in conjunction with the observational method. Although great progress has been made in the field of reliability-based design during the past decade, few geotechnical engineers are familiar with probabilistic approaches to design. In papers II and III, aspects of probabilistic descriptions of soil properties and reliability-based design are discussed. The connection between performing qualitative investigations and potential design savings is discussed in paper III. In the paper, uncertainties are assessed for two sets of investigations, one consisting of more qualitative investigations and hence with less uncertainty. A simplified Bayesian updating technique, referred to as “the multivariate approach”, is used to cross-validate data to reduce the evaluated total uncertainty. Furthermore, reliability-based design was used to compare the two sets of investigations with the calculated penetration depth for a sheet-pile wall. The study is a great example of how a small amount of both time and money (in the pre-investigation phase) can potentially lead to greater savings in the final design.QC 20160201
TRUST, Transparent Underground Structures
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Reeves, G. M. "The application of borehole geophysical logging techniques to geotechnical and hydrogeological investigations." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413145.
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Styler, Mark Anthony. "Investigations into the use of continuous shear wave measurements in geotechnical engineering." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50908.
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The research presented within this thesis covers the development of a means to continuously monitor shear waves in a laboratory triaxial apparatus and down-hole during seismic cone penetration. This work resulted from an investigation of ageing of Fraser River Sand using a bender element triaxial apparatus.
Shear wave propagation times from bender elements were interpreted using published time domain and frequency domain techniques. These techniques provided similar results, but the variability exceeded the effect of ageing. The frequency domain and time domain techniques had different shortcomings. The two techniques could be combined to converge on a single frequency-dependent propagation time that was independent of the trigger signal waveform. This contribution was capable of resolving the small increase in shear wave velocity with age duration.
The frequency domain component of the combined bender element technique could run continuously during an experiment. With this further contribution, it was possible to track the change in shear wave propagation time throughout an experiment. The continuous bender element testing was not observed to influence the effect of ageing.
It was found that in Fraser River Sand ageing had a small effect on the shear wave velocity, no effect on the ultimate strength, and a significant effect on the shear stiffness over the intermediate small-strain range (observed from 0.01 to 1%). The normalized shear stiffness curve shifts to larger strains and becomes more brittle with ageing.
The concepts of the developed continuous bender element method are not restricted to this equipment or even to just bender element testing. The continuous bender element method was adapted to down-hole seismic testing in the field. This contribution resulted in a continuous profile of the shear wave velocity during seismic cone penetration testing that is obtained without stopping the cone penetration.
The developments in this thesis provide a continuous measure of the shear wave velocity through a laboratory experiment and a continuous profile with down-hole penetration depth, i.e. the shear wave velocity is measured every time the other parameters are taken.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Engelhardt, Irina. "Experimental and numerical investigations with respect to the material properties of geotechnical barriers." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970133324.
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Glynn, Mary Eileen 1960. "Geotechnical investigations of two potential sites for the proposed Arizona superconducting super collider." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276641.
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Two sites around the Maricopa and Sierrita Mountains respectively were investigated to provide supporting data for the State of Arizona proposal to the Department of Energy to construct a Superconducting Super Collider (SSC) facility. The main feature of the facility is a 53 mile racetrack shaped tunnel. The proposed Maricopa SSC tunnel passes through three main types of rock--approximately 35 miles of indurated fanglomerates, 10 miles of granodiorites and 8 miles of volcanic and sedimentary rocks. The proposed Sierrita SSC tunnel also passes through three main rock types--approximately 19 miles of indurated fanglomerates, 18 miles of granodiorites and granites and 16 miles of volcanic and associated rocks. Data were obtained from three sources--existing data; field investigations including drill logs and geophysics and laboratory testing. Empirical design approaches were compared with rock classifications (RQD, RMR, Q) at the tunnel horizon. Results indicate mostly routine tunneling at both sites. Recommendations are made for: further logging and testing of existing core; further field mapping; additional boreholes in rock and alluvium; and in situ testing of alluvium.
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Hicks, Malcolm Andrew. "Geotechnical Investigations of Wind Turbine Foundations Using Multichannel Analysis of Surface Waves (MASW)." Thesis, University of Canterbury. Geological Sciences, 2011. http://hdl.handle.net/10092/6519.
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The geophysical technique known as Multichannel Analysis of Surface Waves, or MASW (Park et al., 1999) is a relatively new seismic characterisation method which utilises Rayleigh waves propagation. With MASW, the frequency dependent, planar travelling Rayleigh waves are created by a seismic source and then measured by an array of geophone receivers. The recorded data is used to image characteristics of the subsurface.
This thesis explains how MASW was used as a geotechnical investigation tool on windfarms in the lower North Island, New Zealand, to determine the stiffness of the subsurface at each wind turbine site. Shear‐wave velocity (VS) profiles at each site were determined through the processing of the MASW data, which were then used to determine physical properties of the underlying, weathered greywacke.
The primary research site, the Te Rere Hau Windfarm in the Tararua Ranges of the North Island, is situated within the Esk Head Belt of Torlesse greywacke (Lee & Begg, 2002). Due to the high level of tectonic activity in the area, along with the high rates of weathering, the greywacke material onsite is highly fractured and weathering grades vary significantly, both vertically and laterally. MASW was performed to characterise the physical properties at each turbine site through the weathering profile. The final dataset included 1‐dimensional MASW shear‐wave evaluations from 100 turbine sites. In addition, Poisson’s ratio and density values were characterised through the weathering profile for the weathered greywacke. During the geotechnical foundation design at the Te Rere Hau Windfarm site, a method of converting shear wave velocity profiles was utilised. MASW surveying was used to determine VS profiles with depth, which were converted to elastic modulus profiles, with the input parameters of Poisson’s ratio and density.
This study focuses on refining and improving the current method used for calculating elastic modulus values from shear‐wave velocities, primarily by improving the accuracy of the input parameters used in the calculation.
Through the analysis of both geotechnical and geophysical data, the significant influence of overburden pressure, or depth, on the shear wave velocity was identified. Through each of the weathering grades, there was a non‐linear increase in shear wave velocity with depth. This highlights the need for overburden pressure conditions to be considered before assigning characteristic shear wave velocity values to different lithologies.
Further to the dataset analysis of geotechnical and geophysical information, a multiple variant non‐linear regression analysis was performed on the three variables of shear wave velocity, depth and weathering grade. This produced a predictive equation for determining shear wave
velocity within the Esk Head belt ‘greywacke’ when depth and weathering data are known. If the insitu geological conditions are not comparable to that of the windfarm sites in this study, a set of guidelines have been developed, detailing the most efficient and cost effective method of
using MASW surveying to calculate the elastic modulus through the depth profile of an
investigation site.
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Moisidi, Margarita. "Geological geophysical and seismological investigations for earthquake hazard estimation in western Crete." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4454.
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The purpose of the thesis is the determination of potentially seismic active sources and of the dynamic response evaluation of surface and subsurface structure at sites where the geometric and dynamic properties of the ground can strongly amplify seismic motions. A combination of methods involving the study of geology, geophysics and seismology disciplines permitting cross-comparison of techniques in a robust approach is applied to address these issues. The study area is focused in Kastelli-Kissamou and Paleohora half graben basins in northwestern and southwestern Crete that is located in one of the most seismically active parts of the Africa-Eurasia collision zone. Ground truthed geological field survey, 2D Electrical Resistivity Tomography (ERT), Horizontal to Vertical Spectra Ratio (HVSR) technique using microtremors and microseismicity study are conducted. Microseismicity study involves two different earthquake dataset acquired from a regional permanent network installed on Crete and local temporal network installed on Paleohora. 2D Electrical resistivity tomography (ERT) reveals seven faults in the territory of Kastelli-Kissamou and three faults large scale faults in the territory of Paleohora basin. HVSR technique using microtremors is applied only in the populated area of Kastelli and Paleohora basins and reveals five fault zones in Kastelli and four major fault zones in Paleohora crosscutting the densely populated areas. The effects of the surface and subsurface structure are well patterned in the horizontal to vertical spectra ratios. One amplified clear frequency, two high amplified clear frequencies, broad and flat or low amplitude HVSR peaks attributes the effects of surface and subsurface structure on seismic ground motion. The effects of soft rocks, stiff soils, thick and thin alluvial deposits, fault zones, lateral heterogeneities and discontinuities on seismic ground motion are determined. The higher ground amplification level is observed in Paleohora (A=5.7) compared to Kastelli (A=3.4). Three case studies of building vulnerability evaluation in Paleohora half-graben basin using HVSR technique and microtremors are presented. Temporal seismological network is installed in the territory of Paleohora to study the seismotectonic setting of southwestern Crete. Microseismicity using data from the permanent seismological regional network of Crete is used to compare the seismicity of the study areas.
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Byrne, Byron Walter. "Investigations of suction caissons in dense sand." Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:64c30b2e-155c-4642-9115-5e2bf5667af5.
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Offshore structures are used in a variety of applications ranging from the traditional oil and gas extraction facilities to emerging renewable energy concepts. These structures must be secured to the seabed in an efficient and cost effective manner. A novel approach is to use shallow inverted buckets as foundations, installed by suction, in place of the more usual piles. These foundations lead to cost savings through reduction in materials and in time required for installation. It is necessary to determine how these foundations perform under typical offshore loading conditions so that design calculations may be developed. This thesis presents experimental data from a comprehensive series of investigations aimed at determining the important mechanisms to consider in the design of these shallow foundations for dense sand. Initially the long term loading behaviour (e.g. wind and current) was investigated by conducting three degree of freedom loading {V:M/2R:H} tests on a foundation embedded in dry sand. The results were interpreted through existing work-hardening plasticity theories. The analysis of the data has suggested a number of improved modelling features. Cyclic and transient tests, representing wave loading, were carried out on a foundation embedded in an oil saturated sand. The novel feature of the cyclic loading was that a 'pseudo-random' load history (based on the 'NewWave' theory) was used to represent realistic loading paths. Of particular interest was the tensile load capacity of the foundation. The results observed suggested that for tensile loading serviceability requirements rather than capacity may govern design. Under combined-load cyclic conditions the results indicated that conventional plasticity theory would not provide a sufficient description of response. A new theory, termed 'continuous hyperplasticity' was used, reproducing the results with impressive accuracy. Surprisingly, under the conditions investigated, loading rate was found to have a negligible effect on response.
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Kiflu, Henok Gidey. "Optimized Correlation of Geophysical And Geotechnical Methods In Sinkhole Investigations: Emphasizing On Spatial Variations In West-Central Florida." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4709.
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Abstract
Sinkholes and sinkhole-related features in West-Central Florida (WCF) are commonly identified using geotechnical investigations such as standard penetration test (SPT) borings and geophysical methods such as ground penetrating radar (GPR) and electrical resistivity tomography (ERT). Geophysical investigation results can be used to locate drilling and field testing sites while geotechnical investigation can be used to ground truth geophysical results. Both methods can yield complementary information. Geotechnical investigations give important information about the type of soil, groundwater level and presence of low-density soils or voids at the test location, while geophysical investigations like GPR surveys have better spatial coverage and can resolve shallow stratigraphic indicators of subsidence.
In GPR profiles collected at 103 residential sites in covered-karst terrain in WCF, sinkhole-related anomalies are identified using GPR and SPT methods. We analyze the degree to which the shallow features imaged in GPR correlate spatially with the N-values (blow counts) derived from SPTs at the 103 residential sites. GPR anomalies indicating sinkhole activity are defined as zones where subsurface layers show local downwarping, discontinuities, or sudden increases in amplitude or penetration of the GPR signal. "Low SPT values" indicating sinkhole activity are defined using an optimization code that searched for threshold SPT value showing optimum correlation between GPR and SPT for different optimal depth ranges. We also compared these criteria with other commonly used geotechnical criteria such as weight of rod and weight of hammer conditions.
Geotechnical results were also used to filter the data based on site characteristics such as presence of shallow clay layers to study the effectiveness of GPR at different zones. Subsets of the dataset are further analyzed based on geotechnical results such as clay thickness, bedrock depth, groundwater conditions and other geological factors such as geomorphology, lithology, engineering soil type, soil thickness and prevalent sinkhole type. Results are used to examine (1) which SPT indicators show the strongest correlations with GPR anomalies, (2) the degree to which GPR surveys improve the placement of SPT borings, and (3) what these results indicate about the structure of sinkholes at these sites.
For the entire data set, we find a statistically significant correlation between GPR anomalies and low SPT N-values with a confidence level of 90%. Logistic regression analysis shows that the strongest correlations are between GPR anomalies and SPT values measured in the depth range of 0-4.5 m. The probability of observing a GPR anomaly on a site will decrease by up to 84% as the minimum SPT value increases from 0 to 20 in the general study area. Boreholes drilled on GPR anomalies are statistically significantly more likely to show zones of anomalously low SPT values than boreholes drilled off GPR anomalies. We also find that the optimum SPT criteria result in better correlation with GPR than other simple commonly used geotechnical criteria such as weight of rod and weight of hammer. Better correlations were found when sites with poor GPR penetrations are filtered out from the dataset. The odds ratio showed similar result while the result varied with the depth range, statistics and threshold SPT value (low N- value with optimum correlation), with a maximum observed odds ratio of 3.
Several statistical results suggest that raveling zones that connect voids to the surface may be inclined, so that shallow GPR anomalies are laterally offset from deeper zones of low N-values. Compared to the general study area, we found locally stronger correlation in some sub-regions. For example, the odds ratio found for tertiary hawthorn subgroup were 25 times higher than the odds ratio found for the general study area (WCF).
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Momubaghan, Glory Adeoye. "Geotechnical investigations for the Gautrain Mass Transit Rapid Rail Link over dolomite bedrock in the Centurion area, South Africa." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24891.
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The Gautrain Rapid Rail Link is a state-of-the-art rail route and one of the ten Spatial Development Initiatives planned in Gauteng Province, South Africa. The route comprises two links, namely a link between Tshwane (Pretoria) and Johannesburg and a link between OR Tambo International Airport and Sandton. A total of 10 stations are linked by approximately 80 kilometres of rail along the proposed route. Between Johannesburg and Pretoria in the southern Tshwane region, the rail alignment is underlain by dolomite bedrock for approximately 15km in the vicinity of Centurion between Nelmapius Drive and The Fountains, including nearly 6km elevated on a viaduct. The stability of the rapid rail link constructed over the dolomitic sections was considered a major project risk due to its proneness to sinkholes and subsidences along this route. Construction on heterogeneous soils, pinnacled bedrock and other geohazards posed major challenges to the construction team. To facilitate detailed design and adapt proper foundation options for the viaducts founded over the dolomitic terrain, rigorous and comprehensive ground investigations were conducted by the Bombela Civils Joint Venture (BCJV). This work presents the different ground investigation methods used and how the results have led to the adoption of five suitable foundation solutions namely: large diameter shafts to rock, piles to rock, floating foundations over grouted ground, spread footings on shallow bedrock and concrete U shaped structures. Additional information available on a CD stored at the Merensky Library on 3rd FloorDissertation (MSc)--University of Pretoria, 2012.
Geology
unrestricted
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Örn, Henrik. "Accuracy and precision of bedrock sur-face prediction using geophysics and geostatistics." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171859.
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In underground construction and foundation engineering uncertainties associated with subsurface properties are inevitable to deal with. Site investigations are expensive to perform, but a limited understanding of the subsurface may result in major problems; which often lead to an unexpected increase in the overall cost of the construction project. This study aims to optimize the pre-investigation program to get as much correct information out from a limited input of resources, thus making it as cost effective as possible. To optimize site investigation using soil-rock sounding three different sampling techniques, a varying number of sample points and two different interpolation methods (Inverse distance weighting and point Kriging) were tested on four modeled reference surfaces. The accuracy of rock surface predictions was evaluated using a 3D gridding and modeling computer software (Surfer 8.02®). Samples with continuously distributed data, resembling profile lines from geophysical surveys were used to evaluate how this could improve the accuracy of the prediction compared to adding additional sampling points. The study explains the correlation between the number of sampling points and the accuracy of the prediction obtained using different interpolators. Most importantly it shows how continuous data significantly improves the accuracy of the rock surface predictions and therefore concludes that geophysical measurement should be used combined with traditional soil rock sounding to optimize the pre-investigation program.
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Boller, Ronald C. "Geotechnical investigations at three sites in the South Carolina Coastal Plain that did not liquefy during the 1886 Charleston earthquake." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211385017/.
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Pike, Christopher James. "High resolution acoustic investigations of sub-seabed soils : relationship of wavelet transformed acoustic image to soil properties and some geotechnical parameters." Thesis, Bangor University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265234.
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Dagli, Deniz. "Laboratory Investigations of Frost Action Mechanisms in Soils." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64184.
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Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.
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Wint, Joanne. "Geotechnical site investigation of vegetated slopes." Thesis, Nottingham Trent University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429261.
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Ryan, Christopher R. "Geotechnical investigation of Montrose wetland site." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3723.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xii, 191 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 117-119).
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Pedro, Antonio. "Geotechnical investigation of Ivens Shaft in Lisbon." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/18037.
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Construction of underground structures in urban areas requires a detailed assessment of the associated movements imposed on adjacent structures and services and in particular of any damage that may be caused. The most efficient way of investigating these issues is through the application of advanced numerical analysis, using for instance the finite element method. However, for a useful analysis to be performed, a high quality ground investigation must be conducted in order to derive the necessary soil parameters for numerical modelling. This thesis focuses particularly on the case study of the Ivens shaft located near to the Baixa-Chiado station of the Lisbon Metro, Portugal. This is an underground structure of a complex shape and significant depth, situated in the centre of the city and it is therefore important to assess the influence of its construction on the existing adjacent structures and services. In the first part of the thesis the results of the geotechnical survey performed on the relevant Miocene formations located at the Ivens shaft site are presented and discussed. In particular, the “Areolas de Estefânia” formation was characterised in detail since this layer had not sustained significant investigation in the past, mainly due to difficulties in sampling. From the extensive characterisation undertaken, which included both field and advanced laboratory tests, it was possible to derive a suitable framework for the different formations in terms of strength and stiffness. Such information was then used to calibrate appropriate soil constitutive models for use in the numerical analyses. In this respect, the new generation of algorithms, known as Genetic Algorithms, was employed to increase the efficiency and accuracy of the calibration procedure. The second part of the thesis focuses on the 3D numerical modelling of the excavation of the Ivens shaft, which was performed employing the state-of-the-art software ICFEP (Imperial College Finite Element Program). The results obtained permitted the quantification of the shaft and ground movements and their effect on adjacent structures. Particular attention was given to the influence of the excavation on the Baixa-Chiado station and on the adjacent buildings founded near the ground surface. Finally, a parametric study was carried out in order to investigate a number of shaft parameters that may affect the movements and to provide more general guidance for shaft construction.
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Dong, Yuepeng. "Advanced finite element analysis of deep excavation case histories." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fda7c27d-a132-4975-a73d-e8e009ca38bb.
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Deep excavations have been used worldwide for underground construction, but they also alter the ground conditions and induce ground movements which might cause risks to adjacent infrastructure. Field measurements are normally carried out during excavations to ensure their safety, and also provide valuable data to calibrate the results from the numerical analysis which is an effective way to investigate the performance of deep excavations. This thesis is concerned with evaluating the capability of advanced finite element analysis in reproducing various aspects of observed deep excavation behaviour in the field through back analysis of case histories. The finite element model developed considers both geotechnical and structural aspects such as (i) detailed geometry of the excavation and retaining structures, (ii) realistic material models for the soil, structures and the soil-structure interface, and (iii) correct construction sequences. Parametric studies are conducted first based on a simplified square excavation to understand the effect of several important aspects, e.g. (i) the merit of shell or solid elements to model the retaining wall, (ii) the effect of construction joints in the retaining wall, (iii) the effect of the operational stiffness of concrete structural components due to cracks, (iv) the thermal effect of concrete beams and floor slabs during curing process and due to variation of ambient temperature, (v) the effect of soil-structure interface behaviour, and (vi) the effect of stiffness and strength properties of the soil. Two more complex case histories are then investigated through fully 3D analyses to explore the influence of various factors such as (i) neglecting the small-strain stiffness nonlinearity in the soil model, (ii) the selected K_0 value to represent the initial stress state in the ground, (iii) the appropriate anisotropic wall properties to consider the joints in the diaphragm wall, (iv) the parameters governing the settlements of adjacent buildings and buried pipelines, (v) the effectiveness of ground improvement on reducing the building settlement, (vi) the variation of construction sequences, (vii) the effectiveness of earth berms, and (viii) ignoring the openings in the floor slabs. This research has strong practical implications, but cautions should also be taken in applications, e.g. element types and parameter selection.
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Ibrahim, Jwan Abdul Razzak. "The application of knowledge based technology to geotechnical site investigation." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1420.
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Silva, Ingrid. "Suffusion of Glacial Till Dam Cores : An Experimental Investigation." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71964.
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Suffusion, also called internal instability, is an internal erosion mechanism that occurs in embankment dams when fine-grained particles are washed out of the core soil matrix by seepage. Initiation of internal erosion depends mainly on three major factors: grain size distribution of the soil, stress conditions and hydraulic load; whilst its continuation depends of the filter properties. Broadly graded moraines, as glacial tills, are more susceptible to internal erosion by suffusion than other types of soils used in dams. Most embankment dams in Sweden consist of a central core of glacial till built more than 50 years ago. At the time of its construction, the available guidelines did not include specific grain size boundaries for the core and the filter related to internal erosion susceptibility. Today, several Swedish embankment dams have experienced incident of internal erosion such as leakages and sinkholes, making internal erosion an important safety issue. This circumstance allows raising the questions: How safe are the Swedish embankment dams and what conditions are needed for internal erosion by suffusion to initiate? This research aims to contribute to the assessment of dam safety by giving inputs regarding the characterization of internal erosion by suffusion and the relation among the main factors involved on its occurrence (geotechnical characteristics of soil material, degree of compaction and hydraulic load). This in order to increase the knowledge regarding the critical hydraulic gradient needed to develop suffusion in a given till material with a known degree of compaction. The research includes a laboratory program consistent on suffusion tests, which is an extension of the standard permeability test, and considers post-test examination and diagnosis of the samples. Two main groups of tests were performed: small and large suffusion tests. The small tests serve as a reference of the expected behaviour of soil samples under different boundary and test conditions, which allows optimizing the number of test to be performed in large tests. Results show that suffusion mechanism can be classified as internal suffusion (or filtration) and external suffusion (loss of soil particles from the soil matrix). The influence of compaction degree on the initiation of suffusion is limited in internally stable soils. However, poorly compacted specimens exposed to high hydraulic gradients could develop both internal and external suffusion if the filter is not capable to retain the eroded particles. The hydraulic conductivity of specimens with internal suffusion tends to decrease with a step wise increase of the hydraulic gradient. Such tendency is the result of the matrix of soil reaching equilibrium with the new seepage stresses. The hydraulic conductivity of specimens with external suffusion tends to increase with the increase of the hydraulic gradient.
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Albatal, Ali Hefdhallah Ali. "Advancement of Using Portable Free Fall Penetrometers for Geotechnical Site Characterization of Energetic Sandy Nearshore Areas." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/94608.
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Portable Free Fall Penetrometers (PFFPs) are lightweight tools used for rapid and economic characterization of surficial subaqueous sediments. PFFPs vary in weight, shape and size with options for using add-on units. The different configurations enable deployments in various environments and water depths, including the nearshore zone where conventional methods are challenged by energetic hydrodynamics and limited navigable depth. Moreover, PFFPs offer an opportunity to reduce the high site investigation costs associated with conventional offshore geotechnical site investigation methods. These costs are often a major obstacle for small projects serving remote communities or testing novel renewable energy harvesting machines. However, PFFPs still face issues regarding data analysis and interpretation, particularly in energetic sandy nearshore areas. This includes a lack of data and accepted analysis methods for such environments. Therefore, the goal of this research was to advance data interpretation and sediments characterization methods using PFFPs with emphasis on deployments in energetic nearshore environments.
PFFP tests were conducted in the nearshore areas of: Yakutat Bay, AK; Cannon Beach, AK; and the U.S. Army Corps of Engineers' Field Research Facility's beach, Duck, NC. From the measurements, the research goal was addressed by: (1) introducing a methodology to create a regional sediment classification scheme utilizing the PFFP deceleration and pore pressure measurements, sediment traces on the probe upon retrieval, and previous literature; (2) investigating the effect of wave forcing on the sediments' behavior through correlating variations in sediment strength to wave climate, sandbar migration, and depth of closure, as well as identifying areas of significant sediment mobilization processes; and (3) estimating the relative density and friction angle of sand in energetic nearshore areas from PFFP measurements. For the latter, the field data was supported by vacuum triaxial tests and PFFP deployments under controlled laboratory conditions on sand samples prepared at different relative densities.
The research outcomes address gaps in knowledge with regard to the limited studies available that investigate the sand geotechnical properties in energetic nearshore areas. More specifically, the research contributes to the understanding of surficial sediment geotechnical properties in energetic nearshore areas and the enhancement of sediment characterization and interpretation methods.PHD
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Sayit, Emir. "An Investigation Of Geotechnical Characteristics And Stability Of A Tailings Dam." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614455/index.pdf.
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The objective of this study is to investigate the stability problems in tailing (i.e. mine waste) dams. A tailing dam is an embankment dam (made of natural borrow or tailing material) constructed to retain slurry-like mining wastes that are produced as a result of operation of mines. In the last 30 years, the stability of tailing dams has drawn much attention as a significant number of tailing dam failures have been recorded worldwide. These instability problems caused significant loss of life and damage to property in addition to environmental hazards. In this study causes of failure of tailing dams and their stability problems are investigated with respect to their geometric and material characteristics. Seepage and stability of tailing dams are studied through limit equilibrium method and finite element method. The effects of uncertainties in material properties on the stability of tailings dams is investigated. Within this context, Kastamonu-Kure copper tailings dam is used as a case study and material properties are determined by laboratory tests.
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Wasman, Scott. "Barge impact testing of St. George Island Causeway Bridge geotechnical investigation." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013268.
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Tizzano, Ashley S. "A Geotechnical Investigation of the October 2011 Cedar City Landslide, Utah." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1397555352.
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Jacklitch, Carl Jonathan. "A Geotechnical Investigation of the 2013 Fatal Rockfall in Rockville, Utah." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1464978379.
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Oliver, Andy. "A knowledge based system for the interpretation of site investigation information." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/969/.
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Qiu, Zhenghui. "Investigation of hydro-mechanical particle flow through horizontal orifices." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28112.
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In the modern world, as the global population continues to rise, the need for and recovery of natural resources is becoming ever more relevant. Identifying optimisation solutions for the recovery of granular resources has progressed into one of the most dominant development areas in the mining and processing industries. Two relevant examples from these sectors include the offshore extraction of materials from the ocean floor via hydraulic transport and the processing of mineral particulates through chutes, and hoppers. A common feature of recovery employed in such areas is the rate at which these materials pass through an orifice. The orifice is the interface between the implemented collection or transport system and the targeted material source. Extensive research has been done on the gravitational passing of particles through an orifice, where in contrast, limited knowledge exists on alternative driving factors of flow. The movement of particles induced both mechanically and hydraulically formed the basis of this dissertation in which selected granular materials were experimentally characterised. Specifically, the following were studied: the effect of orifice and particle size, changes in system velocity and the effects of suction. The system encompassed a scaled down model of a real-life application. An experimental and numerical analysis approach was undertaken, where the calibration of the simulated model was dependent on the former. A total of 327 experimental tests were conducted on the flow ability of high sphericity (±95% roundness) glass beads. A numerical model based on the physical parameters was calibrated to further assist in the overall analysis of the system. The model was of a discrete element method (DEM) type. Empirically, it was found that the Beverloo law, an expression used to describe the discharge of particles through a hopper, had many aspects that were dimensionally suited for the study. Through certain boundary assumptions made in the study, the law was in agreement with the stated outputs. The ratio (R) between the orifice (Dₒ) and particle diameter (dₚ) had a significant influence on the entrainment rate, where there existed a region (R > 4) of limiting flow. Changes in the system velocity, were found to have a negligible effect on the overall recovery but a direct relationship with the rate at which the material was collected. The introduction of suction improved the recovery of materials greatly, increasing the mass flow rate by more than 300%. The in-depth analysis on a multitude of orifice configurations, considerably extended the understanding of the behaviour of particles passing through an opening, particularly spherical particles under fluid or mechanical driven flow. Results indicated that there was a lot of potential for improving the optimisation of granular flow. Optimisation in this sense was defined as maximising the recovery (%) or collection rate (kg/s) of the system. Boundary conditions and design guidelines were offered to address this issue. Areas where further research could advance this understanding were highlighted.
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Martin, John Charles. "The development of a knowledge-based system for the preliminary investigation of contaminated land." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/1234/.
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Large areas of the UK have witnessed intense industrialisation since the industrial revolution in the latter part of the 18th Century. Increased environmental awareness and pressure to redevelop brown field sites, have resulted in the majority of civil engineering projects undertaken within the UK encountering some form of contamination. In order to collect the vast amount of information required to assess a potentially contaminated site, a multi-stage site investigation (preliminary investigation, exploratory and detailed investigation) is usually undertaken. The information collected during the investigation allows the three components of the risk assessment process to be identified. These components are the source of contamination, possible pathways for the movement of contaminants and vulnerable targets on and off site. A prototype knowledge-based system (ATTIC Assessment Tool for The Investigation of Contaminated Land) has been developed to demonstrate that knowledge-based technology can be applied to the preliminary stage of the investigation of contaminated land. ATTIC assesses information collected during the preliminary stage of an investigation (past use, geological map, hydrological maps etc.) and assists with the risk assessment process, with the prediction of potential contaminants, hazards and risk to neighbouring areas. The system has been developed, using CLIPS software. It consists of four knowledgebases (source, pathway, target and health and safety knowledge-base), containing 1600 rules. The knowledge within the knowledge-bases was obtained from two main sources. The initial and main source was the technical literature. Obtaining knowledge from technical literature involved reviewing published material, extracting relevant information and converting information into rules suitable for the knowledge-base system. The second source of knowledge was domain experts via a knowledge elicitation exercise. The exercise took the form of a questionnaire relating to the rules and parameters within the system. A Visual Basics interface was also developed in conjunction with the knowledge-based system, in order to allow data entry to the system. The interface uses a series of forms relating to different components within the risk assessment process. On completion of compiling the prototype, the system was validated against a number of case studies. The system predicted the likely contaminants with a reasonable match to those observed, even though the input data for the case studies was limited. The assessment of risks to neighbouring target areas was generally in agreement with the case study reports, matching similar risk values and directions. In addition to the development of the prototype system, a database modelled on the Association of Geotechnical Specialists electronic format for the transfer of ground investigation data was also developed to store preliminary investigation information. The data structures were implemented using Microsoft Access relational database management system software. This allowed the database to be developed within a Microsoft Windows environment.
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Nolutshungu, Lita. "A laboratory investigation on the shear strength characteristics of soil reinforced with recycled linear low-density polyethylene." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29304.
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Since the development of plastics in the 1930’s, plastics have increasingly become widely used for packaging in the commercial market place. With this application being for immediate disposal, the amount of plastic waste generated presents a challenge in the disposal thereof. The risks associated with non-biodegradable products on humans and animal life, pressure on existing landfills and the increasing costs thereof have necessitated the development of alternative options for waste management over the years. Research has resulted in various forms of treatments and recycling processes adopted and implemented as environmentally and economically viable solutions. The use of this recycled material in various applications, such as soil reinforcement addresses the need for engineering solutions with a multifaceted approach which strike a balance between environment, economy and equity. This has been the driving force behind research on the use of alternative materials in engineering design. This study aimed to present an investigation into the use of recycled Linear Low-Density (LLDPE) as reinforcement in Cape Flats sand. To understand the implication of the main aim of the investigation, a review of literature on soil reinforcement theory, various forms of reinforcement material and previous studies was conducted. The selected material for testing was in the form of pellets and flakes produced during the recycling process. Triaxial tests were done on samples where the concentration of the inclusions and compaction effort was varied. The test data presented showed that both pellets and flakes affected the shear strength by plotting Mohr’s circles and the relationship between shear stress and normal stress, which revealed changes in the shear strength parameters. The friction angle was increased by 3.35% at an optimum pellet concentration of 5%. Inclusion of the flakes, however, resulted in a maximum improvement in cohesion of 295% at 0.25% concentration. A discussion on the stress- strain relationship gave an indication on the effect on the stiffness. This showed that the peak shear stress was reached at higher strains when the flakes and pellets were included, compared to the unreinforced sand. Improvements by up to 25% were recorded from the initial 6% strain at peak shear stress of unreinforced sand. In concluding the study, Slide7.0 was used to conduct a 2D finite element analysis using Bishop’s method to analyse the practical application of LLDPE flakes and pellets for slope stability. The optimum shear strength parameters were used in the model, which resulted in an improved global factor of safety meeting the minimum requirement of 1.25.
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Damane, Monica. "An investigation into the volume change characteristics of loess like soil in Mount Moorosi Village in Lesotho." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31497.
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The Mount Moorosi village is situated in the Senqu River Valley of southern Lesotho, within the Stormberg landform. The integrity and aesthetic appearance of nearly all the structures in this area are undermined by recurrent cracks. At present, no apparent institutionalised effort had been conducted to investigate the source of this problem. The crack patterns were associated with the possible volume change of the underlaying loess like soil. This soil has caused a disastrous failure to brittle civil engineering structures in various parts of the world. Its behaviour is attributed to sand and silt particles bonded by minerals, which become active upon saturation and induce hydrocollapse settlement. This study characterised the volume change properties of the underlaid deposits in Mount Moorosi. The research utilised representative samples from trial pits in the study region to perform laboratory experiments such as the Atterberg limits, wet sieving, sedimentation, free swell, x-ray diffraction, scanning electron microscope and slaking. The consolidated undrained tests and hydrocollapse potential were also determined from the GEOCOMP triaxial and Global Digital System oedometer, respectively. Results revealed that Mount Moorosi is generally underlaid by a more than 3 m thickness of low plasticity (9 to 17 %) silty-sandy loess. The material had significant warping (up to 27 mm) in linear shrinkage that illustrated potential inducement of detrimental stresses to the superimposed structures during drying. The identification and quantification of the mineralogy composition clearly evidenced the passive minerals (quartz, feldspar and mica) to be predominant (86 %), while the active phases (kaolinite, carbonates, sulfates, halides, the oxides and hydroxides of aluminum and iron) were subordinate (14 %), which substantiated potential soil settlement upon wetting. Furthermore, the micrographs depicted structures that synergistically enhanced the collapse properties of the tested deposits. These included the porous clays, silts bonded by clay and silts coated with clay, which all rendered a metastable fabric. A comparison of the stressstrain graphical plots from the consolidated undrained tests at the field and saturated moisture contents indicated a drastic reduction (up to 73 %) in deviator stress at saturated water content. This was attributed to the augmentation of the interparticle spaces, caused by a rise of up to 337 kPa in pore water pressure. Shear strength parameters obtained from Mohr’s failure envelopes were also decreased by up to 80 %. The hydrocollapse index measured from the oedometer tests ranged from 10 to 15 % at a vertical stress of 200 kPa. It indicated severe settlement problems for structures constructed on this soil. This was caused by the loss in shear strength of the soil under the saturated conditions and a high slaking mechanism that reached a maximum rating of 4. Generally, the mineralogy composition, morphology, saturated shear strength, slaking and hydrocollapse index collectively indicated the possibility of soil volume decrease. In fact, the check for serviceability limit state demonstrated a settlement that exceeded the tolerable value of 50 mm. The cracks observed on structures were, therefore, related to soil settlement. This study recommends further research on suitable ground techniques to minimise settlement, thereby improving the durability of structures. Moreover, investigations should be conducted to understand the pressure induced by warping during shrinkage.
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Hurley, Shawn J. "Development of a settling column and associated primary consolidation monitoring systems for use in the geotechnical centrifuge : investigation of geotechnical-geophysical correlations /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0009/MQ42397.pdf.
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Proskin, Samuel Albert. "A geotechnical investigation of freeze-thaw dewatering of oil sands fine tailings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0009/NQ34823.pdf.
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Jowett, T. W. D. "An investigation of the geotechnical properties of loess from Canterbury and Marlborough." Thesis, University of Canterbury. Engineering Geology, 1995. http://hdl.handle.net/10092/7580.
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Tunnel gully erosion is common in the loess deposits of the South Island of New Zealand. The loess deposits found on the Wither Hills (Marlborough) and Port Hills (Banks Peninsula) are prone to extensive tunnel gully erosion which has caused significant damage in both rural and urban areas. However, the loess deposits found on the Timaru Downs (South Canterbury) and the hills surrounding Akaroa (Banks Peninsula) are significantly less affected.
Geotechnical tests including pinhole erosion, uniaxial expansion, crumb test and dispersion % were carried out to determine the erosive and dispersive characteristics of loess samples from locations in the aforementioned areas. From this data, the extent to which geotechnical properties influence the incidence of tunnel gully erosion was determined. Other geotechnical characteristics such as grain size, clay mineralogy, exchangeable sodium content and insitu dry density were also evaluated in order to determine the controlling factors on the erosive and dispersive characteristics of the different loess samples.
In general, it was found that laboratory test results did not correlate fully with field erodibility. For instance, the two non tunnel gullied soils exhibited characteristics which suggested that they should be prone to tunnel gully erosion. The lack of correlation between laboratory test data and field erodibility suggests that other factors such as climate, land use and soil profile characteristics are important in determining the occurrence of sub-surface erosion.
A comparison was made of the loess stabilising properties of an enzyme based product known as Endurazyme and quicklime (CaO), a commonly used loess stabiliser. Tests were carried out on samples from the Timaru Downs and the Ahuriri quarry on Banks Peninsula. It was found that Endurazyme has a negligible effect on important geotechnical properties such as erodibility, dispersivity, durability, strength and maximum dry density/optimum moisture content.
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Gillon, Rosemary Jayne Browning. "The role of the ROV within integrated geotechnical and hydrographic site investigation." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/1116.
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The acquisition of marine survey data is traditionally undertaken from surface vessels including boats and temporary rigs. Translation of these techniques to the nearshore zone is a complex task and requires equipment adaptation and. often the sacrifice of data coverage. The remotely operated vehicle (ROV) offers the potential for overcoming some of the standard nearshore survey Concems, providing remote intervention and data acquisition in areas of restricted access. In situ testing is the most efficient and reliable method of acquiring data with minimal sediment disturbance effects. Research has been undertaken into the viability of nearshore cone penetration testing (CPT) which has shown the T-Bar flow round penetrometer to be a possible solution. Data could be acquired in sediments with undrained shear strengths of up to 300 kPa from a bottom crawling ROV weighing 260 kgf and measuring 1 m in length by 0.6 m in width. The collection of sediment cores may be necessary in areas requiring ground truthing for geophysical or in situ investigations. A pneumatic piston corer has been designed and manufactured and is capable of collecting sediment cores up to 400 mm in length, 38 mm in diameter, in sediment with undrained shear strength of 17 kPa. To ascertain additional sediment characteristics in situ, a resistivity subbottom profiling system has also been designed and tested and allows for discrimination between sediment types ranging in size from gravel to silt. The integration of equipment and testing procedures can be fiirther developed through the use of integrated data management approaches such as geographical information systems (GIS). An offthe- shelf GIS, Arclnfo 8, was used to create a GIS containing typical nearshore data using the Dart estuary as a case study location.
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Sikwanda, Charles. "An Investigation of the Effects of Specimen Gripping Systems on Shear Stress at the Geosynthetic/Geosynthetic Interface in Landfill Applications." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31224.
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The use of geosynthetics has rapidly increased in nearly all geotechnical related fields as they allow for innovations, improved performance and cost effectiveness in projects. However, when geosynthetics are installed on sites, particularly on landfill slopes, their interface interaction against the adjacent materials becomes the critical section where shear failure is likely to occur. For this reason, their shear strength behaviour is determined in the laboratory at anticipated site conditions, mainly using a direct shear device to obtain design parameters. These laboratory tests are preferably conducted in accordance with ASTM-D5321 and ASTM-D6243 standards. The direct shear equipment, however, requires the use of an appropriate gripping system for shear to take place in the desired interface. Otherwise, tensile failure within the tested geosynthetics will be generated, resulting in obtaining design parameters which do not represent the actual field performance of the tested geosynthetics. This could lead to unsafe, cost ineffective, etc. design of projects with the respective geosynthetic materials. To date, many laboratories use a variety of gripping systems in a direct shear device to determine the shear design characteristics of geosynthetics and the preferred system remains a topic of concern. As a consequence, there is a large variability in the test results obtained, thus, difficulties in their interpretations. In this research, the effects of two commonly used gripping systems in a direct shear device, namely the nail plate (NP) and sandpaper (SP), have been investigated using a landfill case liner. This liner consisted of the three different classes of geosynthetics which are popularly installed in a landfill i.e. geotextile, geomembrane and geosynthetic clay liner. The results revealed that there exists a dissimilarity in the mobilized shear strength at geosynthetic interface when the NP is used as compared to the utilization of the SP due to the specimen engagement with the respective gripping systems. The exact difference, however, was not established as it varied depending on the interface tested. This highlighted the need to standardize the geosynthetic gripping systems in a direct shear device as it would capture these variations, increase result reproducibility and ease their interpretations.
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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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Bhamidipati, Raghava A. "Use Of Laboratory Geophysical And Geotechnical Investigation Methods To Characterize Gypsum Rich Soils." UKnowledge, 2016. http://uknowledge.uky.edu/ce_etds/45.
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Gypsum rich soils are found in many parts of the world, particularly in arid and semi-arid regions. Most gypsum occurs in the form of evaporites, which are minerals that precipitate out of water due to a high rate of evaporation and a high mineral concentration. Gypsum rich soils make good foundation material under dry conditions but pose major engineering hazards when exposed to water. Gypsum acts as a weak cementing material and has a moderate solubility of about 2.5 g/liter. The dissolution of gypsum causes the soils to undergo unpredictable collapse settlement leading to severe structural damages. The damages incur heavy financial losses every year.
The objective of this research was to use geophysical methods such as free-free resonant column testing and electrical resistivity testing to characterize gypsum rich soils based on the shear wave velocity and electrical resistivity values. The geophysical testing methods could provide quick, non-intrusive and cost-effective methodologies to screen sites known to contain gypsum deposits. Reconstituted specimens of ground gypsum and quartz sand were prepared in the laboratory with varying amounts of gypsum and tested. Additionally geotechnical tests such as direct shear strength tests and consolidation tests were conducted to estimate the shear strength parameters (drained friction angle and cohesion) and the collapse potential of the soils.
The effect of gypsum content on the geophysical and geotechnical parameters of soil was of particular interest. It was found that gypsum content had an influence on the shear wave velocity but had minimal effect on electrical resistivity. The collapsibility and friction angle of the soil increased with increase in gypsum. The information derived from the geophysical and geotechnical tests was used to develop statistical design equations and correlations to estimate gypsum content and soil collapse potential.
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Kanitz, Manuela [Verfasser]. "Experimental and numerical investigation of particle-fluid systems in geotechnical engineering / Manuela Kanitz." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2021. http://d-nb.info/1239730292/34.
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Tisdale, David Charles. "A geotechnical investigation of the Breydon Formation (Holocene), lower Bure Valley, east Norfolk." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248564.
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Soeller, Christopher Philip. "Investigation of the Hydromechanical Effects of Lithostatic Unloading in Open-pit Mines." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:107281.
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Thesis advisor: Alan KafkaThe stability of open-pit mine walls and other geotechnical infrastructure is a function of geometry, material properties and groundwater conditions (pore pressure distribution). A portion of failures are attributed to the effect of pore water pressures within the mine wall slopes. The objective of this research was to investigate the interaction between the increments/decrements of stresses that occur during the lithostatic unloading/excavation of the pit and the increments/decrements of pore water pressures. This interaction can be described by the theory of linear poroelasticity, which incorporates the coupling between changes in fluid pressure and changes in stress in porous media. The results of this thesis are displayed in the form of contour charts and graphs
Thesis (MS) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences
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Gallagher, M. G. "A geotechnical investigation of the Oligocene Lough Neagh Clays of the Crumlin-Glenavy Basin." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382300.
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Bastekin, A. H. "Scottish limestones : An investigation into the geotechnical properties of certain formations and their aggregates." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374508.
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Kiptoo, Dennis Kipngetich. "An investigation of the effect of dynamic and static loading to geosynthetic reinforced pavements overlying a soft subgrade." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20923.
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Construction of roads over soft soils can lead to design and construction related problems linked to the soil's compressibility characteristics and low strength. Failure, in terms of bearing capacity can occur when pavements are constructed over such soft soils. When road pavements, which are constructed over soft soils, are subjected to cyclic traffic loading (dynamic in nature), rapid deterioration of the base layer material and progressive permanent deformation of the surface will occur. This not only reduces the serviceability of the pavement structure but also its design life. In this study, reinforcement geosynthetics (geogrids and geotextiles) were used as reinforcement inclusions within a granular base overlying a soft subgrade of California Bearing Ratio (CBR) less than 2% in a 1.0 m3 steel test box. Firstly, a geotextile/geogrid was placed at the interface between the base layer and subgrade. Thereafter, a combination of the geotextile at the interface (of the base and subgrade) and geogrid within the base layer. Bench scale plate load tests (static and cyclic) were conducted on a 305 mm diameter circular steel plate on the two layer system using a Universal Compression Machine. Static loading was applied at a rate of 1.2 mm/min. Dynamic sinusoidal load wave was applied with a 4 kN seating load that was linearly increased with an incremental load of 4 kN for every 8 cycles at a frequency of 0.2 Hz on a 305 mm circular plate. For both tests, settlement failure of the composite system was considered at a deformation of 75 mm as defined for unpaved roads. The results obtained from the pavement model showed that there was a significant improvement in bearing capacity and reduction in settlement accruing from geosynthetic inclusion as shown by the Bearing Capacity Ratio (BCR) of 1.21, 1.29 and 1.63 for geogrid, geotextile and geogrid-geotextile combinations respectively. Additionally, a Settlement Reduction Factor (SRF) of 18% for geogrid, 23% for geotextile and 31% for the geogrid-geotextile combination resulted. There was also an improvement in extended pavement life as depicted by the Traffic Benefit Ratio (TBR) greater than 1 for all reinforced base layers. An improved performance was realised with the double combination of geotextile at the interface, geogrid at the base.
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Pham, Quy Ngoc [Verfasser]. "An investigation on petrophysical and geotechnical properties of soils using multivariate statistics / Quy Ngoc Pham." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2012. http://d-nb.info/1024699544/34.
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Redshaw, Peter Graham. "A geomorphological and geotechnical investigation of the Roughlands Landslide Complex, Southwest Isle of Wight, UK." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386140/.
Full textAbstract:
The Roughlands Landslide Complex, comprised of slumped blocks, minor scarps, debris slides and a wide graben, is one of the few contemporary landslides on the Isle of Wight to be without major geomorphological or geotechnical investigation. Furthermore, Roughlands poses a puzzle as to the origin and form of its basal shear surface. If compound coastal landslides in ancient marine sediments are typically controlled by a basal shear surface which is guided by a bedding parallel slide prone horizon, how is the shear surface accommodated into the ancient fluvial Wessex Formation, which is largely without such bedding features? The complex is hence subject to a thorough investigation. This includes a rigorous desk study, geomorphological survey, peg network monitoring campaign using DGPS, comprehensive geotechnical testing program, and the installation of two slip-indicators. Although largely stable during the summer, parts of the landslide complex are recorded moving at up to 6.5m yr-1 during the wet winter months, indicating a high sensitivity to groundwater variation. Following an appraisal of eight possible formation mechanisms, it is concluded that the basal shear surface which underlies the Roughlands Landslide Complex is most plausibly guided by the basal surface of a Cretaceous sheet flood deposit. Support for this comes from palaeo-environment interpretation, which reveals various mechanisms by which sheet floods could entrain swelling clays; the excessive recession at Roughlands in comparison to other parts of the southwest coastline, which indicates that geological dip (which varies about the Brighstone Anticline) is influential; the fossil record; relationships with newly recognized faults; and from field observations. Stability analyses find field mobilized shear strength is greater than laboratory determined residual shear strength, which may be in part due to entrained Cretaceous floodplain debris within the slide mass. The unpredictability of landslides on the Wessex Formation also identifies some geotechnical uncertainties which are a concern for all engineering works in ancient fluvial sediments.
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Wong, Wilson W. "Investigation of the Geotechnical Properties of Municipal Solid Waste as a Function of Placement Conditions." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/155.
Full textAbstract:
An investigation of the variability of engineering properties of municipal solid waste as a function of placement conditions was conducted. Limited data have been reported for the engineering properties of municipal solid waste (MSW) as a function of placement conditions. Wastes have high variability of engineering properties due to heterogeneity in composition and component size; influence from time based effects; and presence of compressible solids. Control of moisture content of MSW at the time of waste placement provides opportunity for increased capacity at a given landfill site due to higher compacted unit weight as well as for control of other geotechnical properties. A laboratory experimental test program was conducted on manufactured municipal solid waste (MMSW) that was representative of waste stream in the United States. Large scale test equipment was used to minimize the effects of scaling on results. The experimental program included compaction, compressibility, hydraulic conductivity, and shear strength testing over moisture contents ranging from 11% to 110%. Baseline compaction curves were developed for different compactive efforts. Similar to soils, the MMSW had bell shaped compaction curves that peaked at a maximum dry unit weight and associated optimum moisture content. The compaction curve generated at modified compactive effort had a maximum dry unit weight of 5.1 kN/m3 and optimum moisture content of 66%. Four times modified compactive effort testing resulted in a maximum dry unit weight of 5.9 kN/m3 and corresponding optimum moisture content of 56%. The compaction curve generated for four times modified compactive effort was used as a baseline for subsequent testing. Compression index was calculated from the strain-log stress curves for total stress conditions and is referred to as apparent compression index. Apparent compression index decreased from 1.1 to 0.34 with increasing moisture content. Secant modulus of elasticity was calculated between 1% and 25% strain and ranged from approximately 200 kPa to 4,800 kPa over the range of tested moisture contents. Tangent modulus ranged from 400 kPa to 6,200 kPa between 1% and 25% strain. Both the secant and tangent modulus peaked between 30% and 56% moisture content. Wet of optimum, the moduli of elasticity decreased with increasing moisture content. The hydraulic conductivity was measured under constant head at a hydraulic gradient of 1 and decreased asymptotically from approximately 1.3x10-2 cm/s to 8x10-5 cm/s as the moisture content was increased to optimum. The hydraulic conductivity of the MMSW increased slightly wet of optimum. The internal angle of friction of the MMSW was measured at 15% shear strain and decreased from approximately 40° to 30° with increasing moisture content. Test results demonstrated that both the molding moisture content and dry unit weight have significant impact on the MMSW geotechnical properties, although it appears that molding moisture content ultimately controls the behavior. Based on the results of the tests it was speculated that, similar to clay soils, increases in moisture content allowed for breakdown of the fabric and physical rearrangement of waste components which in turn controlled geotechnical behavior. Overall trends were comparable for MMSW and soil and included: increased dry density and increased stiffness to optimum moisture content; decreased hydraulic conductivity with increased compaction moisture content; and decreased shear strength with increased compaction moisture content. The results of the test program have environmental and economic implications for design and operation of landfills as well as post closure use.
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Loh, Kelvin. "An investigation into the seismic performance and progressive failure mechanism of model geosynthetic reinforced soil walls." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2013. http://hdl.handle.net/10092/8734.
Full textAbstract:
Geosynthetic reinforced soil (GRS) walls involve the use of geosynthetic reinforcement (polymer material) within the retained backfill, forming a reinforced soil block where transmission of overturning and sliding forces on the wall to the backfill occurs. Key advantages of GRS systems include the reduced need for large foundations, cost reduction (up to 50%), lower environmental costs, faster construction and significantly improved seismic performance as observed in previous earthquakes. Design methods in New Zealand have not been well established and as a result, GRS structures do not have a uniform level of seismic and static resistance; hence involve different risks of failure. Further research is required to better understand the seismic behaviour of GRS structures to advance design practices.
The experimental study of this research involved a series of twelve 1-g shake table tests on reduced-scale (1:5) GRS wall models using the University of Canterbury shake-table. The seismic excitation of the models was unidirectional sinusoidal input motion with a predominant frequency of 5Hz and 10s duration. Seismic excitation of the model commenced at an acceleration amplitude level of 0.1g and was incrementally increased by 0.1g in subsequent excitation levels up to failure (excessive displacement of the wall panel). The wall models were 900mm high with a full-height rigid facing panel and five layers of Microgird reinforcement (reinforcement spacing of 150mm). The wall panel toe was founded on a rigid foundation and was free to slide. The backfill deposit was constructed from dry Albany sand to a backfill relative density, Dr = 85% or 50% through model vibration.
The influence of GRS wall parameters such as reinforcement length and layout, backfill density and application of a 3kPa surcharge on the backfill surface was investigated in the testing sequence. Through extensive instrumentation of the wall models, the wall facing displacements, backfill accelerations, earth pressures and reinforcement loads were recorded at the varying levels of model excitation. Additionally, backfill deformation was also measured through high-speed imaging and Geotechnical Particle Image Velocimetry (GeoPIV) analysis. The GeoPIV analysis enabled the identification of the evolution of shear strains and volumetric strains within the backfill at low strain levels before failure of the wall thus allowing interpretations to be made regarding the strain development and shear band progression within the retained backfill.
Rotation about the wall toe was the predominant failure mechanism in all excitation level with sliding only significant in the last two excitation levels, resulting in a bi-linear displacement acceleration curve. An increase in acceleration amplification with increasing excitation was observed with amplification factors of up to 1.5 recorded. Maximum seismic and static horizontal earth pressures were recorded at failure and were recorded at the wall toe. The highest reinforcement load was recorded at the lowest (deepest in the backfill) reinforcement layer with a decrease in peak load observed at failure, possibly due to pullout failure of the reinforcement layer. Conversely, peak reinforcement load was recorded at failure for the top reinforcement layer.
The staggered reinforcement models exhibited greater wall stability than the uniform reinforcement models of L/H=0.75. However, similar critical accelerations were determined for the two wall models due to the coarseness of excitation level increments of 0.1g. The extended top reinforcements were found to restrict the rotational component of displacement and prevented the development of a preliminary shear band at the middle reinforcement layer, contributing positively to wall stability. Lower acceleration amplification factors were determined for the longer uniform reinforcement length models due to reduced model deformation. A greater distribution of reinforcement load towards the top two extended reinforcement layers was also observed in the staggered wall models.
An increase in model backfill density was observed to result in greater wall stability than an increase in uniform reinforcement length. Greater acceleration amplification was observed in looser backfill models due to their lower model stiffness. Due to greater confinement of the reinforcement layers, greater reinforcement loads were developed in higher density wall models with less wall movement required to engage the reinforcement layers and mobilise their resistance.
The application of surcharge on the backfill was observed to initially increase the wall stability due to greater normal stresses within the backfill but at greater excitation levels, the surcharge contribution to wall destabilising inertial forces outweighs its contribution to wall stability. As a result, no clear influence of surcharge on the critical acceleration of the wall models was observed. Lower acceleration amplification factors were observed for the surcharged models as the surcharge acts as a damper during excitation. The application of the surcharge also increases the magnitude of reinforcement load developed due to greater confinement and increased wall destabilising forces.
The rotation of the wall panel resulted in the progressive development of shears surface with depth that extended from the backfill surface to the ends of the reinforcement (edge of the reinforced soil block). The resultant failure plane would have extended from the backfill surface to the lowest reinforcement layer before developing at the toe of the wall, forming a two-wedge failure mechanism. This is confirmed by development of failure planes at the lowest reinforcement layer (deepest with the backfill) and at the wall toe observed at the critical acceleration level. Key observations of the effect of different wall parameters from the GeoPIV results are found to be in good agreement with conclusions developed from the other forms of instrumentation.
Further research is required to achieve the goal of developing seismic guidelines for GRS walls in geotechnical structures in New Zealand. This includes developing and testing wall models with a different facing type (segmental or wrap-around facing), load cell instrumentation of all reinforcement layers, dynamic loading on the wall panel and the use of local soils as the backfill material. Lastly, the limitations of the experimental procedure and wall models should be understood.
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Stanton, Kevin V. "Investigation of Parameters Influencing Reverse Fault Rupture Propagation to the Ground Surface." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1145.
Full textAbstract:
Surface fault rupture poses a serious threat to infrastructure in many seismically active regions, but knowledge about the factors which control the likelihood of surface displacement is limited. Current probabilistic frameworks rely only on fault mechanism and moment magnitude to predict the probability of rupture to the ground surface. However, recent work has shown that there may be other parameters which also deserve consideration. For example, statistical analyses have demonstrated that variation in near surface material stiffness may significantly affect the probability of surface rupture over reverse faults. In addition, numerical investigations indicate that the rupture history of native soil deposits also greatly influences the nature of rupture propagation. Given that evidence exists which suggests multiple variables are at work, this study aimed to improve our understanding of which are most critical for predicting surface fault rupture hazard. We sought to generate physical evidence concerning the impact of near surface soil stiffness, soil type, and rupture history on fault rupture propagation. A 3 meter long by 1 meter wide fault box apparatus was constructed to simulate idealized reverse fault rupture oriented at 45° beneath 60cm of soil. Relatively large dimensions were chosen so that shear wave velocity measurements could be taken directly without interference from the walls of the apparatus. Experiments were conducted on loose sand, dense sand, stiff clay, and soft clay. The same sand was used for both the dense and loose sand experiments and is identified as Monterey #2/16. The clay was a scale model mixture of San Francisco Bay Mud and consisted of kaolinite, bentonite, class C fly ash, and water. Separate batches of clay were mixed with differing final water contents for the stiff and soft clay experiments. In each case, the fault box was filled to 60 cm and rupture was driven to the surface in two phases. The first phase represented an undisturbed native soil deposit with no existing shear band. The second simulated repeat rupture along a pre-existing shear band. The results indicate that increasing material stiffness promotes rupture propagation in both sand and clay. When disturbed soil is re-ruptured, surface rupture occurred much more readily in all materials. Overall, the presence of a pre-existing shear band was shown to have the greatest impact on the likelihood of surface rupture, though both material stiffness and type were also found to have a strong influence as well. The fault box experiments support the findings from previous work as well as shed new light on which parameters are most critical for accurate surface rupture predictions.