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1

Camacho Tauta, Javier Fernando, Óscar Javier Reyes Ortiz y Paula Bibiana Bueno Pumarejo. "Utilización del modelo CAM-CLAY modificado en suelos cohesivos de la Sabana de Bogotá". Ciencia e Ingeniería Neogranadina 14 (1 de noviembre de 2004): 20–29. http://dx.doi.org/10.18359/rcin.1265.

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Con el fin de estudiar el comportamiento mecánico de arcillas típicas de la Sabana de Bogotá, se llevó a cabo un programa de investigación experimental en laboratorio que incluyó ensayos básicos de caracterización, consolidación unidimensional y compresión triaxial consolidada no drenada. De los resultados se obtuvieron los principales parámetros de resistencia y deformabilidad de acuerdo con la teoría del estado crítico. Estos parámetros permiten conformar un modelo de comportamiento bajo el régimen elastoplástico. Se utilizó el modelo Cam-Clay Modificado (CCM) para reproducir las deformaciones resultantes para cada trayectoria de esfuerzos aplicada. Se compararon las curvas producidas por el modelo con respecto a los resultados experimentales, lo que permitió identificar bajo cuales condiciones el modelo simula mejor el comportamiento del suelo y sobre qué variables se debe trabajar para obtener un modelo constitutivo completo.
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2

Ballesteros Granados, Rubby Vanesa. "Obtención de Parámetros del Modelo Hardening Soil Mediante Ensayo CPTu en suelos Blandos de Bogotá". Revista Politécnica 14, n.º 26 (junio de 2018): 89–97. http://dx.doi.org/10.33571/rpolitec.v14n26a8.

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Proyectos de ingeniería como excavaciones, cimentaciones y/o estabilización de taludes, cada día requieren estudios más exigentes que implementen análisis en elementos finitos para obtener resultados más precisos y confiables, esto sólo es posible garantizando la calidad de la información utilizada y definiendo adecuadamente el modelo constitutivo que mejor represente el comportamiento del suelo. Ya sea el modelo Mohr Coulomb, Cam Clay, Hardening Soil u otros disponibles, la obtención de parámetros de entrada con técnicas convencionales de exploración requieren de ejecutar múltiples ensayos que en algunas ocasiones resultan costosos. Por esta razón, los ensayos con técnicas avanzadas de exploración como la prueba de penetración de cono con medición de presión de poros CPTu, representa una buena alternativa para caracterizar el suelo de forma rápida y detallada. Este artículo presenta la obtención de parámetros del modelo Hardening Soil a partir del ensayo CPTu y su validación con resultados de ensayos de laboratorio.
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3

Fattah, Mohammed Y., Firas A. Salman y Bestun J. Nareeman. "Numerical Simulation of Triaxial Test in Clayey Soil Using Different Constitutive Relations". Advanced Materials Research 243-249 (mayo de 2011): 2973–77. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2973.

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The stress paths to which specimens are subjected in triaxial tests together with the yield surfaces, which may be exercised in different models of such a test are simulated. A laboratory testing on undisturbed clay soil samples was performed in order to characterize the stress-strain behaviour of the residual soils in Sao Paulo sedimentary deposit. The sample is tested under isotropically consolidated drained triaxial compression. Strain controlled procedure was used to simulate stress-strain relationships of the soil. Seven models are used; namely: linear elastic, Duncan-Chang hyperbolic, Mohr-Coulomb, Cam clay, modified Cam clay, new Mohr-Coulomb and Cap model. It was concluded that the results of Cam clay and Duncan Chang models are the closest to the experimental data under low confining pressures; 49 and 98 kPa. Both models exhibit parabolic stress-strain relationships while the linear elastic model results are far away from experimental ones especially at large stress levels. At high confining pressure; 196 kPa, the modified Cam clay best correlates the stress and strain.
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4

Nagendra Prasad, K., N. Sulochana y U. Venkata Ramana. "Applicability of Cam-Clay Models for Tropical Residual Soils". Journal of The Institution of Engineers (India): Series A 94, n.º 1 (marzo de 2013): 1–8. http://dx.doi.org/10.1007/s40030-013-0034-y.

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5

Matsuoka, Hajime, Yang-Ping Yao y De’An Sun. "The Cam-Clay Models Revised by the SMP Criterion". Soils and Foundations 39, n.º 1 (febrero de 1999): 81–95. http://dx.doi.org/10.3208/sandf.39.81.

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6

Zhang, Kunyong y Yingbo Ai. "COMPARISON AND APPLICATION OF DIFFERENT ELASTO-PLASTIC CONSTITUTIVE MODELS IN FEM ANALYSIS OF AN EXCAVATED SOIL SLOPE". Journal of Civil Engineering and Management 18, n.º 6 (20 de noviembre de 2012): 802–10. http://dx.doi.org/10.3846/13923730.2012.720931.

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A modified anisotropic elasto-plastic model is presented in this paper based on the frame work of Modified Cam-clay model and Original Sekiguchi-Ohta model by applying a new stress ratio parameter, through which the yield locus and hardening axis in the p-q plane were adjusted to give a more reasonable description of the practical excavation stress path from initial K0 state. Typical excavated soil slope was selected as the illustration example to carry out the finite element numerical analysis by applying four constitutive models (Original Cam-Clay, Modified Cam-Clay, Original Sekiguchi-Ohta and Modified Sekiguchi-Ohta). The calculated displacements of the slope with above different constitutive models were then compared with the measured infield data. It was found the field measured data agree better with the results calculated from modified model, which indicates that the modified anisotropic model is more suitable in the description of the stress path of excavated soils slope after K0 consolidation.
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7

Pye, Christropher Nigel. "The influence of constitutive models on self-boring pressuremeter interpretation in clay". Canadian Geotechnical Journal 32, n.º 3 (1 de junio de 1995): 420–27. http://dx.doi.org/10.1139/t95-046.

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A comparison of the elastic-perfectly plastic (EPP) and hyperbolic (HB) theories for interpreting loading and unloading parts of self-boring pressuremeter (SBP) tests in clay is presented. Computer-aided modelling (CAM) is used to analyze 60 SBP tests in clay to obtain shear modulus (G), undrained shear strength (Su), and in situ total horizontal geostatic stress (σHo). It is shown that the technique of CAM is consistent, repeatable, and simple to use. For all tests analyzed by both models the inferred horizontal geostatic stresses are identical and comparable to "lift-off" measurements. A small systematic difference is found between the two models for the undrained shear strength of soft and stiff clays. The shear modulus valves derived from the EPP model are unrelated to the true modulus of the soil. There is, however, a semiempirical relationship between the HB model and pressuremeter unload–reload (UR) shear modulus. Key words : clay, self-boring pressuremeter, elastic-perfectly plastic, hyperbolic.
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8

Ou, Chang-Yu y Ching-Her Lai. "Finite-element analysis of deep excavation in layered sandy and clayey soil deposits". Canadian Geotechnical Journal 31, n.º 2 (1 de abril de 1994): 204–14. http://dx.doi.org/10.1139/t94-026.

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This paper presents an application of finite-element analysis to deep excavation in layered sandy and clayey soil deposits using a combination of the hyperbolic and the Modified Cam-clay models. In the analysis, the drained behavior of cohesionless soil and the undrained behavior of cohesive soil were simulated using the hyperbolic and Modified Cam-clay models, respectively. A rational procedure for determining soil parameters for each of the models was established. A simulation of the dewatering process during excavation was proposed. The analytical procedure was confirmed through an analysis of three actual excavation cases. Finally, analyses considering pore-water pressure dissipation during the actual elapsed time for each construction phase were carried out. The results indicate that the calculated displacement of a retaining wall during excavation is smaller than that given by undrained analysis. It was thought that some degree of pore-water pressure dissipation actually occurs during the intermediate excavation stages. This results in a decrease in the final deformation of the wall and ground.-surface settlement than would be predicted by undrained analysis. Key words : finite-element analysis, deep excavation, hyperbolic model, Cam-clay model.
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9

De la Morena, Gema, Laura Asensio, Vicente Navarro y Ángel Yustres. "A simple procedure to improve the explicit integration of Cam-Clay models". Computers and Geotechnics 81 (enero de 2017): 207–11. http://dx.doi.org/10.1016/j.compgeo.2016.08.011.

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10

Kuznecov, S. y A. Al' Shemali. "MODIFIED CAM-CLAY MODELS FOR DYNAMIC ANALYSIS OF GRANULAR METAMATERIALS IN EARTHQUAKE ENGINEERING". Construction Materials and Products 4, n.º 3 (12 de agosto de 2021): 54–60. http://dx.doi.org/10.34031/2618-7183-2021-4-3-54-60.

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the problem of protecting buildings and structures from vibrations of natural and artificial nature is im-portant for modern construction. One of such modern methods of protection is seismic pads. The purpose of this work was to study the effect of adding a layer of granular metamaterial under a slab foundation on the vibration of a building under the influence of seismic shear waves (S-waves). To achieve this objective, the finite element method (FEM) was used in combination with Cam-Clay models. The FE model consists of a ten-story superstructure rested on the slab foundation, under which there is a layer of granular metamateri-als. 16 models were created taking into account changes in the values of these parameters (pad thickness; density; cohesion; critical state strength parameter (M); Young's modulus-Poisson's ratio). The dynamic analysis performed using the software package Abaqus/CAE showed the effectiveness of granular met-amaterials in their ability to dissipate seismic energy and significantly reduce vibration transmitted from the ground to the building.
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11

Iodice, Chiara, Raffaele Di Laora y Alessandro Mandolini. "Finite element analyses of energy piles using different constitutive models". E3S Web of Conferences 205 (2020): 05013. http://dx.doi.org/10.1051/e3sconf/202020505013.

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Energy piles are foundation elements having the double scope of transferring structural loads from the structure to the ground and of exchanging heat with the surrounding soil. It follows that pile state of stress and settlement are altered by the time-dependent temperature change in both pile and soil. This work is aimed at investigating the effect of thermal cycles on the behaviour of a single energy pile. To this end, fully coupled thermo-hydro-mechanical analyses have been carried out using the Finite Element code ABAQUS. The single pile is installed in a normally consolidated clay behaving according to different constitutive models involving Mohr-Coulomb, Modified Cam Clay and Hypoplastic. The latter is employed with and without the thermal formulation capable of accounting for the thermal collapse of NC clays during heating. A single free-head pile is considered and the results are presented in terms of pile axial force and settlement developed cycle by cycle.
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12

De la Morena, Gema, Laura Asensio, Ángel Yustres y Vicente Navarro. "A simple procedure to simulate a smooth elastic-plastic transition in Cam-Clay models". Computers and Geotechnics 90 (octubre de 2017): 27–33. http://dx.doi.org/10.1016/j.compgeo.2017.05.020.

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13

Rachdi, Sara, Emad Jahangir, Michel Tijani y Jean-François Serratrice. "Critical state constitutive models and shear loading of overconsolidated clays with deviatoric hardening". Studia Geotechnica et Mechanica 41, n.º 4 (30 de diciembre de 2019): 247–62. http://dx.doi.org/10.2478/sgem-2019-0024.

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AbstractThis paper presents an enhanced constitutive model integrating deviatoric hardening with a modified yield surface for overconsolidated clayey soils in a general framework of Cam-clay type models. Its performance was assessed with the simulation of drained and undrained triaxial tests on three clays at different consolidation states in comparison to two critical state models. The proposed model satisfactorily estimates the shear resistance, while capturing the smooth nonlinearity of the soil response.Shear triaxial tests at constant mean pressure were performed on an overconsolidated marl to study the shear response. Their simulation attests the importance of deviatoric hardening integration.
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14

Islam, Mohammad y Carthigesu Gnanendran. "Non-Associated Flow Rule-Based Elasto-Viscoplastic Model for Clay". Geosciences 10, n.º 6 (10 de junio de 2020): 227. http://dx.doi.org/10.3390/geosciences10060227.

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We develop a non-associated flow rule (NAFR)-based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna’s overstress theory. The NAFR based EVP model comprises three surfaces: the potential surface, the reference surface and the loading surface. Additionally, in the model formulation, assuming the potential surface and the reference surface are identical, we obtain the associated flow rule-based EVP model. Both EVP models require seven parameters and five of them are identical to the Modified Cam Clay model. The other two parameters are the surface shape parameter and the secondary compression index. Moreover, we introduce the shape parameter in the model formulation to control the surface shape and to account for the overconsolidation state of clay. Additionally, we incorporate the secondary compression index to introduce the viscosity of clay. Also, we validate the EVP model performances for the Shanghai clay, the San Francisco Bay Mud (SFBM) clay and the Kaolin clay. Furthermore, we use the EVP models to predict the long-term field monitoring measurement of the Nerang Broadbeach roadway embankment in Australia. From the comparison of model predictions, we find that the non-associated flow rule EVP model captures well a wide range of experimental results and field monitoring embankment data. Furthermore, we also observe that the natural clay exhibits the flow rule effect more compared to the reconstituted clay.
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15

Nepelski, Krzysztof. "Dobór parametrów modelu Cam-Clay dla podłoża lessowego na przykładzie analizy MES 3D budynku rozległego". ACTA SCIENTIARUM POLONORUM - Architectura Budownictwo 19, n.º 2 (21 de septiembre de 2020): 67–81. http://dx.doi.org/10.22630/aspa.2020.19.2.19.

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16

Lorenzo, R., R. P. da Cunha, M. P. Cordão Neto y J. A. Nairn. "Numerical simulation of installation of jacked piles in sand using material point method". Canadian Geotechnical Journal 55, n.º 1 (enero de 2018): 131–46. http://dx.doi.org/10.1139/cgj-2016-0455.

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Pile installation has a great impact on the subsequent mechanical pile response. It is not, however, routinely incorporated in the numerical analyses of deep foundations in sand. Some of the difficulties associated with the simulation of the installation process are related to the fact that large deformations and distortions will eventually appear. The finite element method is not well suited to solve problems of this nature. Hence, an alternative procedure is tested herein, by using the material point method to simulate the installation of statically jacked or pushed-in type piles, which has successfully demonstrated its capacity to deal with this simulation. Two constitutive models were also tested, i.e., the modified Cam clay (MCC) and the subloading Cam clay (SubCam), allowing a clear perception of the great advantage to consider the soil with the SubCam model. The simulations have indeed reproduced some of the important features of the pile installation process, such as the radial stress acting around the pile’s shaft or the shaft’s lateral capacity, among other issues. The numerical results were additionally compared with known (semi-empirical) methods to derive the lateral capacity of the shaft, with a good and practical outcome.
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17

Castro, Jorge y Minna Karstunen. "Numerical simulations of stone column installation". Canadian Geotechnical Journal 47, n.º 10 (octubre de 2010): 1127–38. http://dx.doi.org/10.1139/t10-019.

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This paper describes the results of numerical simulations investigating the installation effects of stone columns in a natural soft clay. The geometry of the problem is simplified to axial symmetry, considering the installation of one column only. Stone column installation is modelled as an undrained expansion of a cylindrical cavity. The excess pore pressures generated in this process are subsequently assumed to dissipate towards the permeable column. The process is simulated using a finite element code that allows for large displacements. The properties of the soft clay correspond to Bothkennar clay, modelled using S-CLAY1 and S-CLAY1S, which are Cam clay–type models that account for anisotropy and destructuration. Stone column installation alters the surrounding soil. The expansion of the cavity generates excess pore pressures, increases the horizontal stresses of the soil, and most importantly modifies the soil structure. The numerical simulations performed allow quantitative assessment of the post-installation value of the lateral earth pressure coefficient and the changes in soil structure caused by column installation. These effects and their influence on stone column design are discussed.
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18

Seyedan, S. y W. T. Sołowski. "Enhancing Constitutive Models for Soils: Adding the Capability to Model Nonlinear Small Strain in Shear". Advances in Civil Engineering 2019 (28 de abril de 2019): 1–11. http://dx.doi.org/10.1155/2019/6016350.

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The deviatoric stress-deviatoric strain relationship in soils is highly nonlinear, especially in the small strain range. However, the constitutive models which aim to replicate the small strain nonlinearity are often complex and rarely used in geotechnical engineering practice. The goal of this study is to offer a simple way for updating the existing constitutive models, widely used in geotechnical practice, to take into account the small strain shear modulus changes. The study uses an existing small strain relationship to derive a yield surface. When the yield surface is introduced to an existing soil model, it enhances the model with the nonlinear deviatoric stress-deviatoric strain relationship in the small strain range. The paper also gives an example of such a model enhancement by combining the new yield surface with the Modified Cam Clay constitutive model. The validation simulations of the undrained triaxial tests on London Clay and Ham River sand with the upgraded constitutive models replicate the experiments clearly better than the base models, without any changes to existing model parameters and the core source code associated with the base model.
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19

Irani, Mazda. "Predicting Geomechanical Dynamics of Steam-Assisted Gravity-Drainage Process. Part II: Modified Cam-Clay Model". SPE Journal 25, n.º 06 (14 de mayo de 2020): 3366–85. http://dx.doi.org/10.2118/201186-pa.

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Summary In Part I of this study (Irani 2018), the geomechanical effects in the reservoir associated with steam-assisted gravity drainage (SAGD) steam chamber growth was evaluated on the basis of two core assumptions: reservoir yield behavior follows that of the Mohr-Coulomb (MC) dilative behavior, and the reservoir stress response follows that of a drained sand. In Part I, it was shown that although the dilative model nicely described the shearing and the sheared zone thickness at the front of the SAGD steam chamber, it could not predict the displacements associated with cold dilation in SAGD reservoirs, in which cold dilation refers to vertical displacement created in the zone ahead of the heated zone caused by isotropic unloading generated by the pore pressure increase and the increase in far-field horizontal stress. In cold dilation, the stresses do not reach the critical state line (CSL), which defines the yield surface and should, therefore, be analyzed considering elastic behavior. A modified Cam-Clay (MCC) model, however, can be used to describe the behavior of the oil sand in the cold dilation zone before reaching the CSL. In this study and as an extension to the results presented in Part I, strains developed in the reservoir during SAGD operation are calculated using an MCC model, and the associated oil rate enhancement and displacements are evaluated. The vertical strains and displacements are compared with measured values from the extensive monitoring program conducted at the Underground Test Facility (UTF) in the late 1980s. Two aspects of geomechanical effects are compared between the cap models (Part II) and dilative models (Part I): first, prediction of the sheared zone thickness and its effect on SAGD production enhancement, and second, prediction of vertical and horizontal displacements. It is shown that consideration of the material model effects on production rates are negligible for both models and that the MCC model can predict displacements in both the heated and cold zones of the reservoir reasonably accurately. Although dilative constitutive models can be used to predict horizontal and vertical displacements in the heated zone quite accurately, they lack the ability to predict the response in the “cold dilation zone.” Another main advantage of using an MCC model is that the MCC model provides a better description of a stress path and how the reservoir mobility can affect reservoir dilation, especially in the cold dilation zone.
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20

Sheng, Daichao, Yangping Yao y John P. Carter. "A volume–stress model for sands under isotropic and critical stress states". Canadian Geotechnical Journal 45, n.º 11 (noviembre de 2008): 1639–45. http://dx.doi.org/10.1139/t08-085.

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A simple volume–stress model for granular soils under isotropic and critical stress states is presented. The model is formulated in the double logarithmic space of void ratio versus mean stress. It has the same number of parameters as used in the Cam Clay models to describe isotropic compression, with one additional parameter to define the critical state curve. The model can qualitatively describe a number of unique features of sand behaviour. Comparison with experimental data indicates that the model is able to predict well the volume change of a range of different sands subjected to isotropic and triaxial compression.
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21

Agraine, Hana y Meriem Fakhreddine Bouali. "Numerical Modelling of Oedometer Test". Selected Scientific Papers - Journal of Civil Engineering 15, n.º 2 (1 de diciembre de 2020): 127–36. http://dx.doi.org/10.1515/sspjce-2020-0025.

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Abstract The oedometric test is a test widely used in civil engineering. The main objective of this article has been to investigate the primary consolidation behaviour of the intact soil samples by comparing the results obtained from finite element analysis computations in PlAXIS2D with the experimental result of the soil samples obtained from the site of the Al-Ahdab oil field in the east of Iraq. Three different material models were utilized during the finite element analysis, comparing the performance of the more advanced constitutive Soft Soil material model against the modified Cam Clay and Mohr-Coulomb material models. Numerical results of Oedomter test show that the Soft Soil model behaviour is the most appropriate model to describe the observed behaviour.
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22

Einav, Itai. "Soil mechanics: breaking ground". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, n.º 1861 (13 de septiembre de 2007): 2985–3002. http://dx.doi.org/10.1098/rsta.2007.0009.

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In soil mechanics, student's models are classified as simple models that teach us unexplained elements of behaviour; an example is the Cam clay constitutive models of critical state soil mechanics (CSSM). ‘Engineer's models’ are models that elaborate the theory to fit more behavioural trends; this is usually done by adding fitting parameters to the student's models. Can currently unexplained behavioural trends of soil be explained without adding fitting parameters to CSSM models, by developing alternative student's models based on modern theories? Here I apply an alternative theory to CSSM, called ‘breakage mechanics’, and develop a simple student's model for sand. Its unique and distinctive feature is the use of an energy balance equation that connects grain size reduction to consumption of energy, which enables us to predict how grain size distribution (gsd) evolves—an unprecedented capability in constitutive modelling. With only four parameters, the model is physically clarifying what CSSM cannot for sand: the dependency of yielding and critical state on the initial gsd and void ratio.
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23

Prado, Jose Manuel. "Plastic Behaviour of Green Powder Metallurgical Compacts". Materials Science Forum 534-536 (enero de 2007): 305–8. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.305.

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The results of monotonic and cyclic uniaxial compression tests, in which the deviatoric component of the stress is predominant, carried out on green and recrystallized iron compacts with different levels of density are presented and discussed in order to analyse the macro and micromechanisms governing the mechanical behaviour of non-sintered PM materials. The plastic deformation of the particles, especially at the contact areas between neighbouring particles, produces an internal friction responsible for the main features observed in the behaviour of green metallic compacts. These experimental results show important discrepancies with the plasticity models, Cam-Clay and Drucker-Prager Cap, used to simulate the powder compaction stage. Possible causes for these discrepancies are pointed out.
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24

Silvestri, Vincenzo, Ghassan Abou-Samra y Christian Bravo-Jonard. "Effect of flow rules and elastic strains on pressuremeter test results in dense sand". Canadian Geotechnical Journal 46, n.º 2 (febrero de 2009): 160–67. http://dx.doi.org/10.1139/t08-108.

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Simple numerical methods that allow to obtain stress and strain paths in sand during self-boring pressuremeter tests are presented in this paper. The material is considered to undergo deformation in drained and plane-strain conditions. The flow rules of Rowe, Cambridge-type (Cam clay and Nova) model, and the sawtooth model are used in the analysis. Elastic strains are also considered in relation with the flow rule of Rowe. The proposed approach has been evaluated using a reference pressuremeter test performed on Ticino sand in a calibration chamber. The results indicate that the stress–strain–volume change responses of the sand predicted by the various models are quite similar, with and without consideration of the elastic strain components.
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25

Pham, Hung Van, Huy Quang Dang, Lam Phuc Dao y Long Khac Nguyen. "Study on arching effect in the embankment over pile - reinforced soft soil". Journal of Mining and Earth Sciences 61, HTCS6 (31 de diciembre de 2020): 19–25. http://dx.doi.org/10.46326/jmes.htcs2020.03.

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The paper employes 3D numerical modeling to analyze the soil arching mechanism within embankment by FLAC3D code, based on the finite difference method (FDM). To consider the pile group effect, the 3D mesh of four pile has been created. Related to the constitutive models, the embankment is used Mohr - Coulomb model, the soft soil is represented by modified Cam - clay model, and footing and piles are employed by elasticity model. The numerical results focus on the soil arching phenomena in terms of stress distribution on piles and soft soil, the stress concentration ratio and the stress reduction ratio. Additionally, the axial force along pile and the settlements of embankment, soft soil and pile are studied.
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26

Shang, C., I. Csaba Sinka y J. Pan. "Material Data for Modelling Density Distributions in Green Parts". Materials Science Forum 672 (enero de 2011): 207–14. http://dx.doi.org/10.4028/www.scientific.net/msf.672.207.

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Die compaction of powders is a process which involves filling a die with powder, compaction using rigid punches to form a dense compact and ejection from the die. The process can be treated as a large deformation plasticity problem. The challenge is to develop and implement appropriate constitutive models that capture the evolution of the powder from a loose state into a dense compact. In this paper we describe data analysis procedures and calibrate classic incremental plasticity models, such as Cam-Clay, Drucker-Prager cap models. The complexity of the models is increased from models with a hardening law to more complex constitutive models using density as state variable. The compaction behaviour of a range of powder materials is characterized experimentally. Numerical simulation of the compaction of simple parts and complex parts is demonstrated. The merits of various models are evaluated in terms of the balance between complexity and practicality. The discussion is illustrated with case studies exploring the applicability of the models specific to various powder pressing scenarios.
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27

Indraratna, Buddhima, Chamari Bamunawita y Hadi Khabbaz. "Numerical modeling of vacuum preloading and field applications". Canadian Geotechnical Journal 41, n.º 6 (1 de diciembre de 2004): 1098–110. http://dx.doi.org/10.1139/t04-054.

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This study describes the effect of unsaturation at a drain boundary on the behaviour of a single prefabricated vertical drain subjected to vacuum preloading based on a two-dimensional plane strain finite element model incorporating the modified Cam–Clay model. Unsaturation of soil adjacent to the drain can occur due to mandrel withdrawal or application of vacuum pressure through prefabricated vertical band drains (PVDs). Following initial laboratory simulation in a large-scale radial drainage consolidometer, the authors have attempted to explain the observed retardation of pore pressure dissipation through a series of models, which consider the effect of unsaturation at the drain-soil interface. The results indicate that the introduction of an unsaturated soil layer adjacent to a PVD improves the accuracy of numerical predictions. Lastly, a multidrain analysis is conducted to study the behaviour of an embankment stabilized with vertical drains subjected to vacuum preloading, and the field measurements are compared with a series of numerical model predictions.Key words: consolidation, embankment, finite element method, settlement, soft clay, vacuum preloading, vertical drains.
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28

Hegde, A. M. y T. G. Sitharam. "Three-dimensional numerical analysis of geocell-reinforced soft clay beds by considering the actual geometry of geocell pockets". Canadian Geotechnical Journal 52, n.º 9 (septiembre de 2015): 1396–407. http://dx.doi.org/10.1139/cgj-2014-0387.

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Due to its complex honeycomb structure, the numerical modeling of the geocell has always been a big challenge. Generally, the equivalent composite approach is used to model the geocells. In the equivalent composite approach, the geocell–soil composite is treated as the soil layer with improved strength and stiffness values. Though this approach is very simple, it is unrealistic to model the geocells as the soil layer. This paper presents a more realistic approach of modeling the geocells in three-dimensional (3D) framework by considering the actual curvature of the geocell pocket. A square footing resting on geocell reinforced soft clay bed was modeled using the “fast Lagrangian analysis of continua in 3D” (FLAC3D) finite difference package. Three different material models, namely modified Cam-clay, Mohr–Coulomb, and linear elastic were used to simulate the behaviour of foundation soil, infill soil and the geocell, respectively. It was found that the geocells distribute the load laterally to the wider area below the footing as compared to the unreinforced case. More than 50% reduction in the stress was observed in the clay bed in the presence of geocells. In addition to geocells, two other cases, namely, only geogrid and geocell with additional basal geogrid cases were also simulated. The numerical model was systematically validated with the results of the physical model tests. Using the validated numerical model, parametric studies were conducted to evaluate the influence of various geocell properties on the performance of reinforced clay beds.
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29

Diarra, H., V. Mazel, V. Busignies y P. Tchoreloff. "Comparative study between Drucker-Prager/Cap and modified Cam-Clay models for the numerical simulation of die compaction of pharmaceutical powders". Powder Technology 320 (octubre de 2017): 530–39. http://dx.doi.org/10.1016/j.powtec.2017.07.077.

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30

Bandehzadeh, Omid, Masoud Mirmohammad Sadeghi, Mohammad Ali Rowshanzamir y Alborz Hajian Nia. "A comparison between performances of the behavioral models in evaluating load-bearing capacity of piles in fine-grained unsaturated soil". Ukrainian Journal of Ecology 8, n.º 1 (13 de febrero de 2018): 233–39. http://dx.doi.org/10.15421/2018_207.

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<p>Virtually all structural piles are installed on the top of groundwater level, and these piles are located on unsaturated soils. In this case, the negative orifice water pressure caused by capillarity significantly influences the mechanical behavior of unsaturated soils. Consequently, structural suction is highly important to load-bearing capacity of loads. In this paper, an evaluation was drawn between the Mohr-Coulomb, modified Cam-Clay, and Barcelona behavioral models using the finite-difference method, and results of studies conducted to estimate load-bearing capacity in the static state were provided. The behavioral model guidelines matched the laboratory models. To estimate soil vividness on the suction level of concern, the water-soil curve (showing suction patterns in relation to moisture) utilized. The general tendencies of settlement gotten by the numerical examination are reliable with pile insert test results. Results suggest that the Barcelona personality model (BBM) yields more realistic estimates of load capacity as it looks at the effect of unsaturated soil suction.</p>
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31

Gnanendran, C. T., G. Manivannan y S. CR Lo. "Influence of using a creep, rate, or an elastoplastic model for predicting the behaviour of embankments on soft soils". Canadian Geotechnical Journal 43, n.º 2 (1 de febrero de 2006): 134–54. http://dx.doi.org/10.1139/t05-090.

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The predictability of the behaviour of an embankment constructed on a soft soil with three types of fully coupled finite element analysis models; namely a rate-formulated elasto-viscoplastic, a creep-formulated elasto-viscoplastic, and modified Cam clay (MCC) elastoplastic material model for the foundation soil is examined in this paper. The well documented geotextile reinforced Sackville test embankment was chosen for analyses using the three finite element models. Details of the analyses carried out using the three models and the results are discussed in comparison with field performance. All three models were found to be capable of predicting the behaviour of this embankment reasonably well. The creep model gave slightly better overall predictions of the behaviour compared to the rate and MCC models and therefore is considered to be better for predicting the time-dependent behaviour of this embankment. However, it requires the coefficient of secondary compression of the foundation soft soil as an additional input parameter and consumes more computing resources and time. In contrast, this study suggests that the MCC model is also capable of giving reasonably good overall predictions using less computing resources and time and therefore is sufficient for predicting the performance of embankments on soft soils.Key words: embankment, soft soil, geosynthetic reinforcement, analysis, viscoplasticity, creep.
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32

Zhang, Ming Yi, Hai Lei Kou y Wei Zhang. "Numerical Simulation of the Successive Penetration of Jacked Pile in Layered Cohesive Soil and Sand". Advanced Materials Research 261-263 (mayo de 2011): 1449–53. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1449.

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Different constitutive models is piecewise adopted including modified Cam clay model in cohesive soil and Drucker–Prager model in sand in order to simulate the penetration of jacked piles with ABAQUS more reasonably in layered soil particularly in interactive cohesive and sandy layered soil. Simultaneously, a series of other measures are taken including smoothing the angular corner between the tip and the shaft of a pile in the penetration process, allowing elastic slip even local detachment in pile-soil interface, making the initial stress equilibrium in layered soil come true by means of unconventional multiple calculation and so on. Combining with engineering example, the process of successive penetration of jacked pile in layered soil of having significantly different properties and stiff soil-interlayer in soft soil is simulated and calculated successfully, reflecting the abrupt change phenomenon of stress around pile and jacking resistance. And so the conclusion of numerical analysis is consistent with the in-situ observations.
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33

François, B., L. Tacher, Ch Bonnard, L. Laloui y V. Triguero. "Numerical modelling of the hydrogeological and geomechanical behaviour of a large slope movement: the Triesenberg landslide (Liechtenstein)". Canadian Geotechnical Journal 44, n.º 7 (1 de julio de 2007): 840–57. http://dx.doi.org/10.1139/t07-028.

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Using advanced hydrogeological and geomechanical finite element modelling, it has been possible to model the mechanical behaviour of a large slope movement, the Triesenberg landslide. This slope is located along the Rhine valley in the Principality of Liechtenstein and covers an area of around 5 km2, which includes two villages. Pore-water pressure fields calculated by the hydrogeological model were used as input for the geomechanical model. The results obtained through numerical simulation agree fairly well with field measurements of peak velocity, spatial and temporal distribution of velocity, and total displacements. Such results were obtained using a modified Cam-Clay elastoplastic constitutive model for which the required material parameters were obtained through careful geotechnical tests. These finite element models were carried out in two and three dimensions to gradually improve the understanding of the physical phenomena governing the hydrogeological conditions and the movements of the slope.Key words: landslides, slope movement, hydromechanical coupling, elastoplasticity, numerical modelling.
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34

Kwiecień, Sławomir. "Influence of Load Plates Diameters, Shapes of Columns and Columns Spacing on Results of Load Plate Tests of Columns Formed by Dynamic Replacement". Sensors 21, n.º 14 (16 de julio de 2021): 4868. http://dx.doi.org/10.3390/s21144868.

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The dynamic replacement method is used to strengthen the subgrade of objects, usually up to 5 to 6 m thick. After the improvement process, acceptance tests in the form of load testing are carried out. Interpretation of the test results can cause some difficulties. Dynamic replacement results in a situation where columns of different shapes, loaded with plates of diameters usually smaller than the head diameter and in the vicinity of adjacent columns, are subjected to load tests. In order to demonstrate the influence of these factors, a spatial model of soil strengthened by dynamic replacement, comprising four material zones, was calibrated on the basis of load testing. The following models were used in the analysis: linear-elastic, elastic–perfectly plastic (Coulomb–Mohr) and elastic–plastic with isotropic hardening (Modified Cam-Clay). This formed the basis for 105 numerical models, which took into account the actual shapes of the columns made at various spacings, subjected to load tests with plates of various diameters. The analyses of the settlements, calculated moduli and stress distribution in the loaded system showed how the results were significantly influenced by mentioned factors. This implies that the interpretation of the results of load tests should be based on advanced spatial numerical analyses, using appropriate constitutive models and including the considered factors.
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35

Cui, Yu Jun, Nabil Sultan y Pierre Delage. "A thermomechanical model for saturated clays". Canadian Geotechnical Journal 37, n.º 3 (1 de junio de 2000): 607–20. http://dx.doi.org/10.1139/t99-111.

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A thermomechanical model for saturated clays is proposed within the framework of recent extensions of the Cam-Clay model. The results of some tests found in the literature are analyzed, and the main features of the thermomechanical behaviour of clays are identified. The effect of the overconsolidation ratio (OCR) on the volume change of a soil (expansion-contraction) submitted to heating is well established using experimental data obtained for selected soils by various authors. However, existing models need to be modified to correctly model this feature. For this reason, a new volumetric thermal plastic mechanism is developed that allows for the prediction of plastic strains at higher OCR values. The overconsolidation effect observed when heating a normally consolidated soil is also modelled. Particular attention is paid to the coupling and hardening phenomena related to the combined effects of stress and temperature. A qualitative validation is made by examining the response of the model under a given thermomechanical path. Comparison with existing thermomechanical experimental results shows that the model can provide satisfactory predictions.Key words: clays, constitutive modelling, temperature effects, deformation, elastoplasticity, radioactive waste disposal.
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36

Fattah, Mohammed Y., Kais T. Shlash y Nahla M. Salim. "Effect of Reduced Zone on Time-Dependent Analysis of Tunnels". Advances in Civil Engineering 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/963502.

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The problem of the proposed “Baghdad metro line” which consists of two routes of 32 km long and 36 stations is analyzed. The tunnel is circular in cross-section with a 5.9 m outer diameter. The finite element analyses were carried out using elastic-plastic and modified Cam clay models for the soil. The excavation has been used together with transient effects through a fully coupled Biot formulation. All these models and the excavation technique together with Biot consolidation are implemented into finite-element computer program named “Modf-CRISP” developed for the purpose of these analyses. The results indicate that there is an inward movement at the crown and this movement is restricted to four and half tunnel diameters. A limited movement can be noticed at spring line which reaches 0.05% of tunnel diameter, while there is a heave at the region below the invert, which reaches its maximum value of about 0.14% of the diameter and is also restricted to a region extending to 1.5 diameters. The effect of using reduced zone on excess pore water pressure and surface settlement (vertical and horizontal) was also considered and it was found that the excess pore water pressure increases while the settlement trough becomes deeper and narrower using reduced .
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37

Seta, E., T. Kamegawa y Y. Nakajima. "Prediction of Snow/Tire Interaction Using Explicit FEM and FVM". Tire Science and Technology 31, n.º 3 (1 de julio de 2003): 173–88. http://dx.doi.org/10.2346/1.2135267.

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Abstract A three-dimensional prediction model has been developed in which the interaction between snow and a rolling tire with tread pattern is considered. An explicit finite element method (FEM) and a finite volume method (FVM) are used to model tire and snow respectively. Snow deformation is calculated by the Eulerian formulation to solve the complex interaction between snow and tire tread pattern. Coupling between a tire and snow is automatically computed by the coupling element. Numerical modeling of snow is essential to the tire performance prediction on snow. In this study, snow is assumed to be homogeneous and considered to be an elasto-plastic material. The Mohr-Coulomb yield model, in which the yield stress is a single function of pressure, is adopted. This function is investigated by tire traction tests under a wide range of tire contact pressures using several tires with different inflation pressures and patterns. The predicted results using the Mohr-Coulomb yield model are compared with those using the Capped Drucker-Pragger and the Cam-Clay yield models. Snow traction of a tire featuring different tread patterns is simulated by this technology. Results are shown to be in good qualitative agreement with experimental data.
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38

Rab, M. A., S. Chandra, P. D. Fisher, N. J. Robinson, M. Kitching, C. D. Aumann y M. Imhof. "Modelling and prediction of soil water contents at field capacity and permanent wilting point of dryland cropping soils". Soil Research 49, n.º 5 (2011): 389. http://dx.doi.org/10.1071/sr10160.

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Field capacity (FC) and permanent wilting point (PWP) are two critical input parameters required in various biophysical models. There are limited published data on FC and PWP of dryland cropping soils across north-western Victoria. Direct measurements of FC and PWP are time-consuming and expensive. Reliable prediction of FC and PWP from their functional relationships with routinely measured soil properties can help to circumvent these constraints. This study provided measured data on FC using undisturbed samples and PWP as functions of geomorphological unit, soil type, and soil texture class for dryland cropping soils of north-western Victoria. We used a balanced, nested sampling strategy and developed functional relationships of FC and PWP with routinely measured soil properties using residual maximum likelihood based mixed-effects regression modelling. Using the data, we also tested the adequacy of nine published pedotransfer functions (PTFs) in predicting FC and PWP. Significant differences were observed among the three soil types and nine texture classes for most soil properties. FC and PWP were higher for Grey Vertosols (FC 43.7% vol, PWP 29.1% vol) than Hypercalcic Calcarosols (38.4%, 23.5%) and Red Sodosols (20.2%, 9.2%). Of the several functional relationships developed for prediction of FC and PWP, a quadratic single-predictor model based on dg (geometric mean particle size diameter) performed better than other models for both FC and PWP. It was nearly bias-free, with a root mean square error (RMSE) of 3.18% vol and an R2 of 93% for FC, and RMSE 3.47% vol and R2 89% for PWP. Another useful model for FC was a slightly biased, two-predictor quadratic model based on clay and silt, with RMSE 3.14% vol and R2 94%. For PWP, two other possibly useful, though slightly biased, models included a single-predictor quadratic model based on clay (RMSE 3.45% vol, R2 89%) and a three-predictor model based on clay, silt, and σg (geometric standard deviation of particle size diameter) (RMSE 3.27% vol, R2 90%). We observed a strong quadratic relationship of FC with PWP (RMSE 1.61% vol, R2 98%). This suggests the possibility to further improve the prediction of FC indirectly through PWP. These predictive models for FC and PWP, though developed for the dryland cropping soils of north-western Victoria, may be applicable to other regions with similar soil and climatic conditions. Some validation is desirable before these models are confidently applied in a new situation. Of the nine published PTFs, the multiple linear regression and artificial neural network based NTh5 for FC and NTh3 and CAM for PWP performed better on our data for the prediction of FC and PWP. The root mean square deviation of these PTFs, for both FC and PWP, was higher than the RMSE of our models. Our models are therefore likely to perform better under the dryland cropping soils of north-western Victoria than these PTFs. As a safeguard against arriving at optimistic inferences, we suggest that the modelling of functional relationships needs to account for the hierarchical structure of the sampling design using appropriate mixed effects regression models.
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39

Tsugawa, Juliana Keiko, Roberto Cesar de Oliveira Romano, Rafael Giuliano Pileggi y Maria Eugenia Gimenez Boscov. "Review: Rheology concepts applied to geotechnical engineering". Applied Rheology 29, n.º 1 (3 de marzo de 2020): 202–21. http://dx.doi.org/10.1515/arh-2019-0018.

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AbstractThe effect of time on soil properties, noticeable in many earthworks, is recognized by geotechnicians. For example, secondary compression and aging pre-consolidation are considered in geotechnical design, and strain rate is standardized in geotechnical laboratory and field tests. Elastic-plastic models, from rigid-perfect plastic to Modified Cam Clay, which do not consider the effects of time, solve most geotechnical problems. However, solutions for prolonged settlements, landslides, debris flow and mudflow could profit from a deeper understanding of rheological models. In fact, rheological concepts, despite not always clearly stated, have been used to address some of these problems, and may also be important for using new materials in geotechnical practice (tailings, sludge, soil-polymer mixtures and other materials with water content higher than the liquid limit). This paper introduces basic concepts of rheology for geotechnicians, specially highlighting viscoelasticity under simple shear stress, which explains with reasonable accuracy well known phenomena dependent on time in soils. The objective is to bring geotechnicians to rheology and show another important tool to access geotechnical problems. On the other hand, a brief explanation of geotechnical tests is presented for rheologists not acquainted with geotechnical engineering. Geotechnical tests procedures are discussed in the light of rheology concepts, terminology is clarified, examples of application of rheology in geotechnics are presented, and determination of soil rheological parameters by traditional geotechnical tests as well as by tests on concrete is commented.
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40

Abu-Farsakh, Murad, Ahmad Souri, George Voyiadjis y Firouz Rosti. "Comparison of static lateral behavior of three pile group configurations using three-dimensional finite element modeling". Canadian Geotechnical Journal 55, n.º 1 (enero de 2018): 107–18. http://dx.doi.org/10.1139/cgj-2017-0077.

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The lateral resistance of three pile group configurations was investigated using three dimensional (3-D) finite element modeling. The three pile groups considered in the study were a vertical pile group, a battered pile group, and a mix of vertical and battered piles in a group. The study was motivated by the full-scale static load test that was conducted on the M19 pier foundation in the I-10 twin span bridge in Louisiana. The static lateral resistance of the M19 battered pile group was investigated previously using a 3-D finite element simulation and verified with the aid of experimental results. In the present study, the M19 battered pile group model was used as the basis for the vertical and mixed pile groups for developing their 3-D finite element models. The nonlinear material behavior was accounted for using elastoplastic constitutive models such as the concrete damaged plasticity model and the anisotropic modified Cam clay model. The lateral resistance of the pile groups was investigated in terms of load–displacement, axial load, bending moment, pile damage, soil resistance, and p-multipliers. The results show that the battered pile group had the largest lateral resistance, followed by the mixed and vertical pile groups, respectively. The largest lateral load share was carried by the two middle rows in the battered pile group, while it was in the leading row in the vertical and mixed pile groups. The soil resistance profiles show that the vertical pile group mobilized greater soil resistance than the battered and mixed pile groups at the same lateral load. The back-calculated p-multipliers are the highest in the battered pile group case, followed by the mixed and vertical pile groups, respectively.
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41

Fall, Meissa, Serigne Sam Samb, Mapathé Ndiaye, Oustasse A. Sall y Fatou Samb. "Cam-Clay Models Using Castem 2000<sup>©</sup> and Plaxis<sup>©</sup> for the Study of the Slope Stability of the “Corniche Ouest” of the Dakar Peninsula (Senegal, West Africa)". Geomaterials 01, n.º 02 (2011): 51–58. http://dx.doi.org/10.4236/gm.2011.12009.

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42

Mitew-Czajewska, M. "Evaluation of Hypoplastic Clay Model for Deep Excavation Modelling". Archives of Civil Engineering 62, n.º 4 (1 de enero de 2016). http://dx.doi.org/10.1515/ace-2015-0098.

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AbstractThis paper presents an evaluation of the Hypoplastic Clay constitutive model for finite element analysis of deep excavations and displacements induced by excavations in the influence zone. A detailed description and formulation of the Hypoplastic Clay soil model is included. A parametric case study of a deep excavation executed in Pliocene clays is presented. FE analysis was performed using several soil models (Mohr-Coulomb, Modified Mohr-Coulomb, Drucker-Prager, Modified Cam-Clay, Hypoplastic Clay) and the results were compared to in-situ displacements measurements taken during construction. Final conclusions concerning the suitability of the Hypoplastic Clay model for deep excavation modelling in terms of accurate determination of horizontal displacements of the excavation wall, the uplift of the bottom of excavation, and, most importantly, vertical displacements of the terrain in the vicinity of the excavation are presented.
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43

Contreras, Ulysses, Guangbu Li, Craig D. Foster, Ahmed A. Shabana, Paramsothy Jayakumar y Michael D. Letherwood. "Soil Models and Vehicle System Dynamics". Applied Mechanics Reviews 65, n.º 4 (1 de julio de 2013). http://dx.doi.org/10.1115/1.4024759.

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The mechanical behavior of soils may be approximated using different models that depend on particular soil characteristics and simplifying assumptions. For this reason, researchers have proposed and expounded upon a large number of constitutive models and approaches that describe various aspects of soil behavior. However, there are few material models capable of predicting the behavior of soils for engineering applications and are at the same time appropriate for implementation into finite element (FE) and multibody system (MBS) algorithms. This paper presents a survey of some of the commonly used continuum-based soil models. The aim is to provide a summary of continuum-based soil models and examine their suitability for integration with the large-displacement FE absolute nodal coordinate formulation (ANCF) and MBS algorithms. Special emphasis is placed on the formulation of soils used in conjunction with vehicle dynamics models. The implementation of these soil models in MBS algorithms used in the analysis of complex vehicle systems is also discussed. Because semiempirical terramechanics soil models are currently the most widely used to study vehicle/soil interaction, a review of classical terramechanics models is presented in order to be able to explain the modes of displacements that are not captured by these simpler models. Other methods such as the particle-based and mesh-free models are also briefly reviewed. A Cam–Clay soil model is used in this paper to explain how such continuum-mechanics based soil models can be implemented in FE/MBS algorithms.
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44

Wang, Shun y Wei Wu. "Validation of a simple hypoplastic constitutive model for overconsolidated clays". Acta Geotechnica, 19 de noviembre de 2020. http://dx.doi.org/10.1007/s11440-020-01105-5.

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AbstractHypoplastic constitutive models are able to describe history dependence using a single nonlinear tensorial function with a set of parameters. A hypoplastic model including a structure tensor for consolidation history was introduced in our previous paper (Wang and Wu in Acta Geotechnica, 2020, 10.1007/s11440-020-01000-z). The present paper focuses mainly on the model validation with experiments. This model is as simple as the modified Cam Clay model but with better performance. The model requires five parameters, which are easy to calibrate from standard laboratory tests. In particular, the model is capable of capturing the unloading behavior without introducing loading criteria. Numerical simulations of element tests and comparison with experiments show that the proposed model is able to reproduce the salient features of normally consolidated and overconsolidated clays.
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45

Todorov, Miroslav. "MODEL PARAMETERS FOR THE DYNAMIC BEHAVIOR OF BURIED PIPES-PART 1". Proceedings of International Structural Engineering and Construction 8, n.º 1 (julio de 2021). http://dx.doi.org/10.14455/isec.2021.8(1).gfe-06.

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Pipeline systems are an integral part of modern human activity for much of the accompanying processes of lifestyle and industry. The design and construction of underground facilities solves one major problem-improving the quality of life by deploying the systems near the consumer, without intruding on the human environment. The necessity for more efficient behavior prognosis and evaluation as well as better design of buried pipelines during and after various actions (including geologic and seismic hazards) is directly related to the knowledge of their working mechanism, while aiming to prevent incidents which impact the human life. A number of additional parameters describing the conditions, behavior and effects of the pipeline system, going beyond the conventional Eurocode methods, is a requirement for the scope of this study. This study covers a comprehensive research system based on laboratory and in situ techniques, numerical analyses and the creation of interaction parameters of a buried pipe with soil massif in dynamic situations. Laboratory analyses were conducted in a laboratory triaxial state with cyclic shear strains. All parameters that were defined by constitution models-Mohr-Coulomb, Hardening soil model, Modified Cam-Clay based in a Plaxis software were traced. In the final phase of the publication (Part 2) the implementation and evaluation of the formulated parameters and results of the study are demonstrated.
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