scholarly journals Study on arching effect in the embankment over pile - reinforced soft soil

2020 ◽  
Vol 61 (HTCS6) ◽  
pp. 19-25
Author(s):  
Hung Van Pham ◽  
Huy Quang Dang ◽  
Lam Phuc Dao ◽  
Long Khac Nguyen ◽  
Keyword(s):  
Stress Reduction ◽  
Soft Soil ◽  
Constitutive Models ◽  
Pile Group ◽  
3D Numerical Modeling ◽  
Soil Arching ◽  
Modified Cam Clay ◽  
Stress Concentration Ratio ◽  
Pile Group Effect ◽  
Cam Clay

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.

Evaluation of Plate Anchors Capacity in Saturated Soils Using Different Constitutive Models

2014 ◽  
Author(s):  
Zahra Aghazadeh ◽  
M. S. Rahman ◽  
M. A. Gabr
Keyword(s):  
Soft Soil ◽  
Constitutive Models ◽  
Control Approach ◽  
Pull Out ◽  
Saturated Clay ◽  
Element Simulation ◽  
Modified Cam Clay ◽  
Plate Anchor ◽  
Plate Anchors ◽  
Cam Clay

Evaluation of the uplift capacity of plate anchors in saturated clay is an important aspect in offshore anchoring of various structures. In most of the literature reviewed, a constitutive model such as Tresca or Mohr-Coulomb has been used in analyses. There exists a need to study the anchors’ pull out capacity using other advanced soil models and discern differences in results. This study presents the results of finite element simulation of a rectangular or circular plate anchor in saturated clay. The capacity factors (Nc) of the plate are assessed through the application of displacement control approach and the results are compared to the lower bound solution as well as to data obtained from similar studies available in the literature. In addition to Mohr-Coulomb model, two other constitutive models are used to represent the soil deformation. These are Modified Cam-Clay, and Soft Soil models. Undrained effective stress analyses are conducted using the computer program PLAXIS. A series of analyses using different embedment depths are performed for all three constitutive models. Results as Nq value from the three constitutive models are presented and discussed.

Numerical Simulation of the Successive Penetration of Jacked Pile in Layered Cohesive Soil and Sand

2011 ◽  
Vol 261-263 ◽  
pp. 1449-1453
Author(s):  
Ming Yi Zhang ◽  
Hai Lei Kou ◽  
Wei Zhang
Keyword(s):  
Soft Soil ◽  
Constitutive Models ◽  
Cohesive Soil ◽  
Layered Soil ◽  
Penetration Process ◽  
Stress Equilibrium ◽  
Modified Cam Clay ◽  
Stiff Soil ◽  
Cam Clay

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.

scholarly journals Validation of a simple hypoplastic constitutive model for overconsolidated clays

2020 ◽  
Author(s):  
Shun Wang ◽  
Wei Wu
Keyword(s):  
Laboratory Tests ◽  
Constitutive Models ◽  
Standard Laboratory ◽  
Hypoplastic Model ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Overconsolidated Clays ◽  
Hypoplastic Constitutive Model ◽  
Comparison With Experiments ◽  
Cam Clay

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.

Analysis of the Treatment of Soft Soil Considering Rheological Property

2012 ◽  
Vol 518-523 ◽  
pp. 4417-4420
Author(s):  
Yong Quan Li ◽  
Jun Fu Chen ◽  
Yun Zhong Tu ◽  
Xiao Tao Yuan
Keyword(s):  
Finite Element ◽  
Soft Soil ◽  
Plastic Model ◽  
Clay Model ◽  
Foundation Treatment ◽  
Soft Foundation ◽  
Modified Cam Clay ◽  
Tailing Dam ◽  
Double Yield ◽  
Cam Clay

viscoelasto-plastic; double yield surface; equivalent sand wall; finite element; Abstract. Based on double yield elastoplastic model, one viscoelasto-plastic model is dealt with in detail. The method of transferring to equivalent sand wall is introduced when soft soil is treated by plastic drainage plate. The viscoelasto-plastic model and modified Cam-Clay model are applied into the finite element calculation of soft foundation treatment of a tailing dam. By comparison, it can be got that the displacement calculated by the viscoelasto-plastic model is closer to monitoring data than that calculated by modified Cam-Clay model. It demonstrates the reasonableness and efficiency of the viscoelasto-plastic model．

scholarly journals Finite element analyses of energy piles using different constitutive models

2020 ◽  
Vol 205 ◽  
pp. 05013
Author(s):  
Chiara Iodice ◽  
Raffaele Di Laora ◽  
Alessandro Mandolini
Keyword(s):  
Finite Element ◽  
Constitutive Models ◽  
Single Pile ◽  
Finite Element Analyses ◽  
Energy Pile ◽  
State Of Stress ◽  
Modified Cam Clay ◽  
Energy Piles ◽  
Fully Coupled ◽  
Cam Clay

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.

Numerical simulation of installation of jacked piles in sand using material point method

2018 ◽  
Vol 55 (1) ◽  
pp. 131-146 ◽  
Author(s):  
R. Lorenzo ◽  
R.P. da Cunha ◽  
M.P. Cordão Neto ◽  
J.A. Nairn
Keyword(s):  
Constitutive Models ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Deep Foundations ◽  
Lateral Capacity ◽  
Pile Installation ◽  
Modified Cam Clay ◽  
Semi Empirical ◽  
Cam Clay

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.

Numerical Analysis of One-Dimensional Consolidation in Fine-Grained Soils

2020 ◽  
Vol 857 ◽  
pp. 334-340
Author(s):  
Hana Agraine ◽  
Meriem Fakhreddine Bouali ◽  
Abdelhamid Messameh
Keyword(s):  
Soft Soil ◽  
Constitutive Law ◽  
Excess Pore Pressure ◽  
Fine Grained ◽  
Finite Element Software ◽  
Clay Model ◽  
Modified Cam Clay ◽  
Degree Of Consolidation ◽  
Cam Clay ◽  
Good Agreement

The purpose of this study is to discuss which constitutive law can describes at best the observed behavior of Silt and Gravelly Clay on the basis of experimental and analytical results. To find numerical solution for saturated soils in oedometer test Plaxis 2D the finite element software was used. In order to obtain the compressibility, excess pore pressure and degree of consolidation curves; two constitutive laws were used in this work: the Soft Soil Model ‘SSM’ and the Modified Cam Clay Model ‘MCC’. Predicted results were found in good agreement with measurements obtained from experimental test and analytical solutions. The Soft Soil is in good agreement with experimental results in the compressibility curve; however the Modified Cam Clay Model is the most appropriate if compared with the analytical solution.

scholarly journals COMPARISON AND APPLICATION OF DIFFERENT ELASTO-PLASTIC CONSTITUTIVE MODELS IN FEM ANALYSIS OF AN EXCAVATED SOIL SLOPE

2012 ◽  
Vol 18 (6) ◽  
pp. 802-810 ◽  
Author(s):  
Kunyong Zhang ◽  
Yingbo Ai
Keyword(s):  
Constitutive Models ◽  
Fem Analysis ◽  
Stress Path ◽  
Soil Slope ◽  
Modified Model ◽  
Stress Ratio Parameter ◽  
Modified Cam Clay ◽  
Frame Work ◽  
Reasonable Description ◽  
Cam Clay

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.

scholarly journals Validation of a simple hypoplastic constitutive model for overconsolidated clays

2021 ◽  
Author(s):  
shun wang ◽  
Wei Wu
Keyword(s):  
Laboratory Tests ◽  
Constitutive Models ◽  
Standard Laboratory ◽  
Hypoplastic Model ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Overconsolidated Clays ◽  
Hypoplastic Constitutive Model ◽  
Comparison With Experiments ◽  
Cam Clay

Hypoplastic 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, https://doi.org/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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