scholarly journals Numerical analysis on zone-divided deep excavation in soft clays using a new small strain elasto–plastic constitutive model

2021 ◽  
Author(s):  
Afnan Younis Tanoli ◽  
Bin Yan ◽  
Yong-lin Xiong ◽  
Guan-lin Ye ◽  
Usama Khalid ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Constitutive Model ◽  
Small Strain ◽  
Deep Excavation ◽  
Soft Clays

3D numerical analysis of pile response due to soil movements induced by an adjacent deep excavation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tamir Amari ◽  
Mohamed Nabil Houhou
Keyword(s):  
Numerical Analysis ◽  
Parametric Study ◽  
Pile Group ◽  
Small Strain ◽  
Nonlinear Behaviour ◽  
Single Pile ◽  
Deep Excavation ◽  
Braced Excavation ◽  
Content Type ◽  
Pile Response

Purpose This paper aims to investigate single pile and pile group responses due to deep braced excavation-induced soil movement in soft clay overlying dense sand. The analysis focuses first on the response of vertical single pile in terms of induced bending moment, lateral deflection, induced axial force, skin resistance distribution and pile settlement. To better understand the single pile behaviour, a parametric study was carried out. To provide further insights about the response of pile group system, different pile group configurations were considered. Design/methodology/approach Using the explicit finite element code PLAXIS 3 D, a full three-dimensional numerical analysis is carried out to investigate pile responses when performing an adjacent deep braced excavation. The numerical model was validated based on the results of a centrifuge test. The relevance of the 3 D model is also judged by comparison with the 2 D plane strain model using the PLAXIS 2 D code. Findings The results obtained allowed a thorough understanding of the pile response and the soil–pile–structure interactions phenomenon. The findings reveal that the deep excavation may cause appreciable bending moments, lateral deflections and axial forces in nearby piles. The parametric study showed that the pile responses are strongly influenced by the excavation depth, relative pile location, sand density, excavation support system and pile length. It also showed that the response of a pile within a group depends on its location in relation to the other piles of the pile group, its distance from the retaining wall and the number of piles in the group. Originality/value Unlike previous studies which investigated the problem in homogeneous geological context (sand or clay), in this paper, the pile response was thoroughly studied in a multi-layered soil using 3 D numerical simulation. To take into account the small-strain nonlinear behaviour of the soil, the Hardening soil model with small-strain stiffness was used in this analysis. For a preliminary design, this numerical study can serve as a practical basis for similar projects.

Numerical analysis of a multipropped excavation in stiff clay

1998 ◽  
Vol 35 (1) ◽  
pp. 115-130 ◽  
Author(s):  
Charles WW Ng ◽  
B Simpson ◽  
M L Lings ◽  
DFT Nash
Keyword(s):  
Numerical Analysis ◽  
Small Strain ◽  
Bending Moments ◽  
Deep Excavation ◽  
Case Record ◽  
Highly Nonlinear ◽  
Nonlinear Stress ◽  
Simple Drainage ◽  
Stiff Clay ◽  
Very High

This paper presents the procedures and the results of numerical analyses of a multipropped deep excavation at Lion Yard, Cambridge, using the nonlinear Brick model. The computed results are compared with the comprehensive case record. The observed small deflections and bending moments of the wall, low prop forces, and relatively small ground movements during the main excavation have been taken into account. Shear strains which developed around the site during the main excavation were generally less than 0.3%. Significant reduction of lateral stress in the ground during wall installation and the highly nonlinear stress-strain characteristics of the Gault Clay are the chief reasons for the observed unusual behaviour. The Gault Clay exhibits first yield at a threshold shear strain of about 0.001%, beyond which the stiffness deteriorates significantly from an initial very high value. This high stiffness at very small strains may be due to cementation bonding between soil particles, as a result of the presence of calcium carbonate. Simple drainage assumptions for the stiff fissured clay on both sides of the diaphragm wall appear to be inadequate for design analyses.Key words: numerical analysis, multipropped excavation, Gault Clay, nonlinear brick model, small strain stiffness.

The Further Exploration of Applying Small-Strain and Large-Strain Formulations to SMA

2012 ◽  
Vol 529 ◽  
pp. 228-235
Author(s):  
Jie Yao ◽  
Yong Hong Zhu
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Uniaxial Tension ◽  
Driving Force ◽  
Research Team ◽  
Large Strain ◽  
Small Deformation ◽  
Small Strain ◽  
Proportional Loading ◽  
The Difference

Recently, our research team has been considering to applying shape memory alloys (SMA) constitutive model to analyze the large and small deformation about the SMA materials because of the thermo-dynamics and phase transformation driving force. Accordingly, our team use simulations method to illustrate the characteristics of the model in large strain deformation and small strain deformation when different loading, uniaxial tension, and shear conditions involve in the situations. Furthermore, the simulation result unveils that the difference is nuance concerning the two method based on the uniaxial tension case, while the large deformation and the small deformation results have huge difference based on shear deformation case. This research gives the way to the further research about the constitutive model of SMA, especially in the multitiaxial non-proportional loading aspects.

A large deformation framework for shape memory polymers: Constitutive modeling and finite element implementation

2012 ◽  
Vol 24 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Mostafa Baghani ◽  
Reza Naghdabadi ◽  
Jamal Arghavani
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Shape Memory ◽  
Finite Deformation ◽  
Deformation Gradient ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Small Strain ◽  
Internal Variables

Shape memory polymers commonly experience both finite deformations and arbitrary thermomechanical loading conditions in engineering applications. This motivates the development of three-dimensional constitutive models within the finite deformation regime. In the present study, based on the principles of continuum thermodynamics with internal variables, a three-dimensional finite deformation phenomenological constitutive model is proposed taking its basis from the recent model in the small strain regime proposed by Baghani et al. (2012). In the constitutive model derivation, a multiplicative decomposition of the deformation gradient into elastic and inelastic stored parts (in each phase) is adopted. Moreover, employing the mixture rule, the Green–Lagrange strain tensor is related to the rubbery and glassy parts. In the constitutive model, the evolution laws for internal variables are derived during both cooling and heating thermomechanical loadings. Furthermore, we present the time-discrete form of the proposed constitutive model in the implicit form. Using the finite element method, we solve several boundary value problems, that is, tension and compression of bars and a three-dimensional beam made of shape memory polymers, and investigate the model capabilities as well as its numerical counterpart. The model is validated by comparing the predicted results with experimental data reported in the literature that shows a good agreement.

Constitutive model for the numerical analysis of phase transformation in polycrystalline shape memory alloys

2012 ◽  
Vol 32-33 ◽  
pp. 155-183 ◽  
Author(s):  
Dimitris Lagoudas ◽  
Darren Hartl ◽  
Yves Chemisky ◽  
Luciano Machado ◽  
Peter Popov
Keyword(s):  
Phase Transformation ◽  
Numerical Analysis ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory
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