scholarly journals Large-deformation finite-element modelling of earthquake-induced landslides considering strain-softening behaviour of sensitive clay

2019 ◽  
Vol 56 (7) ◽  
pp. 1003-1018 ◽  
Author(s):  
Naveel Islam ◽  
Bipul Hawlader ◽  
Chen Wang ◽  
Kenichi Soga
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Large Scale ◽  
Slope Failure ◽  
Strain Softening ◽  
Limit Equilibrium ◽  
Fe Analysis ◽  
Plastic Shear ◽  
Fe Modelling ◽  
Sensitive Clay

Large-scale landslides in sensitive clays cannot be explained properly using the traditional limit equilibrium or Lagrangian-based finite-element (FE) methods. In the present study, dynamic FE analysis of sensitive clay slope failures triggered by an earthquake is performed using a large-deformation FE modelling technique. A model for post-peak degradation of undrained shear strength as a function of accumulated plastic shear strain (strain-softening) is implemented in FE analysis. The progressive development of “shear bands” (the zone of high plastic shear strains) that causes the failure of a number of soil blocks is simulated successfully. Failure of a slope could occur during an earthquake and also at the post-quake stage until the failed soil masses come to a new static equilibrium. Upslope retrogression and downslope runout of the failed soil blocks are examined for varying geometries and soil properties. The present FE simulations can explain some of the conditions required for different types of seismic slope failure (e.g., spread, flowslide or monolithic slides) to be triggered, as observed in the field.

scholarly journals A case study and implication: particle finite element modelling of the 2010 Saint-Jude sensitive clay landslide

Landslides ◽  
2019 ◽  
Vol 17 (5) ◽  
pp. 1117-1127 ◽  
Author(s):  
Xue Zhang ◽  
Liang Wang ◽  
Kristian Krabbenhoft ◽  
Stefano Tinti
Keyword(s):  
Finite Element ◽  
Slope Failure ◽  
Strain Softening ◽  
Failure Process ◽  
Numerical Approach ◽  
Strength Reduction ◽  
Particle Finite Element Method ◽  
Computational Framework ◽  
Sensitive Clay

AbstractModelling of landslides in sensitive clays has long been recognised as a challenge. The strength reduction of sensitive clays when undergoing plastic deformation makes the failure proceed in a progressive manner such that a small slope failure may lead to a series of retrogressive failures and thus to an unexpected catastrophic landslide. The clay in the entire process may mimic both solid-like (when it is intact) and fluid-like (when fully remoulded, especially for quick clays) behaviours. Thereby, a successful numerical prediction of landslides in sensitive clays requires not only a robust numerical approach capable of handling extreme material deformation but also a sophisticated constitutive model to describe the complex clay behaviour. In this paper, the particle finite element method (PFEM) associated with an elastoviscoplastic model with strain softening is adopted for the reconstruction of the 2010 Saint-Jude landslide, Quebec, Canada, and detailed comparisons between the simulation results and available data are carried out. It is shown that the present computational framework is capable of quantitatively reproducing the multiple rotational retrogressive failure process, the final run-out distance and the retrogression distance of the Saint-Jude landslide. Furthermore, the failure mechanism and the kinematics of the Saint-Jude landslide and the influence of the clay viscosity are investigated numerically, and in addition, their implications to real landslides in sensitive clays are discussed.

TWO-DIMENSIONAL LARGE DEFORMATION FINITE ELEMENT MODELLING OF SENSITIVE CLAY LANDSLIDES

2020 ◽  
Author(s):  
Bipul Hawlader ◽  
◽  
Chen Wang ◽  
Ripon Karmaker ◽  
Didier Perret ◽  
...  
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Finite Element Modelling ◽  
Two Dimensional ◽  
Element Modelling ◽  
Sensitive Clay

scholarly journals Factor of Safety Reduction Factors for Accounting for Progressive Failure for Earthen Levees with Underlying Thin Layers of Sensitive Soils

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Adam J. Lobbestael ◽  
Adda Athanasopoulos-Zekkos ◽  
Josh Colley
Keyword(s):  
Finite Element ◽  
Strain Softening ◽  
Progressive Failure ◽  
Limit Equilibrium ◽  
Thin Layers ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Limit Equilibrium Methods ◽  
The Stability ◽  
Reduction Factors

The effects of progressive failure on flood embankments with underlying thin layers of soft, sensitive soils are investigated. Finite element analysis allows for investigation of strain-softening effects and progressive failure in soft and sensitive soils. However, limit equilibrium methods for slope stability analysis, widely used in industry, cannot capture these effects and may result in unconservative factors of safety. A parametric analysis was conducted to investigate the effect of thin layers of soft sensitive soils on the stability of flood embankments. A flood embankment was modeled using both the limit equilibrium method and the finite element method. The foundation profile was altered to determine the extent to which varying soft and sensitive soils affected the stability of the embankment, with respect to progressive failure. The results from the two methods were compared to determine reduction factors that can be applied towards factors of safety computed using limit equilibrium methods, in order to capture progressive failure.

Large-deformation finite element analysis of the interaction between concrete cut-off walls and high-plasticity clay in an earth core dam

2017 ◽  
Vol 34 (4) ◽  
pp. 1126-1148 ◽  
Author(s):  
Xiang Yu ◽  
Degao Zou ◽  
Xianjing Kong ◽  
Long Yu
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Small Strain ◽  
Fe Analysis ◽  
Hyperbolic Model ◽  
High Plasticity ◽  
Fe Method ◽  
Content Type ◽  
Earth Core ◽  
High Plasticity Clay

Purpose A large, uneven settlement that is unfavourable to dam safety can occur between a concrete cut-off wall and the high-plasticity clay of earth core dam built on alluviums. This issue has been often studied using the small-strain finite element (FE) method in previous research. This paper aims to research the interaction behaviour between a concrete cut-off wall and high-plasticity clay using large-deformation FE analyses. Design/methodology/approach The re-meshing and interpolation technique with a small-strain (RITSS) method was performed using an independently developed program and adopted for large-deformation FE analyses, and a suitable element size for the high-plasticity clay region was suggested. The layered construction process of an earth core dam built on thick alluviums was simulated using the RITSS method incorporating a hyperbolic model for soil. Findings The RITSS method is an effective technique for simulating the soil–structure interaction during dam construction. The RITSS analysis predicted a higher maximum principle stress of the concrete cut-off wall and higher stress levels in the high-plasticity clay region than small-strain FE analysis. Originality/value A practical method for large-deformation FE analysis was advised and was used for the first time to study the interaction between a concrete cut-off wall and high-plasticity clay in dam engineering. Large deformation in the high-plasticity clay was handled using the RITSS method. Moreover, the penetration process of the concrete cut-off wall into the high-plasticity clay was captured using a favourable element shape and mesh density.

scholarly journals Flexible Temporary Shield in Soft and Sensitive Clay: 3D FE Modelling of Experimental Field Test

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Miah Alam ◽  
Omar Chaallal ◽  
Bertrand Galy
Keyword(s):  
Field Test ◽  
Numerical Study ◽  
Earth Pressure ◽  
Maximum Load ◽  
Reduction Factor ◽  
Fe Analysis ◽  
Soil Pressure ◽  
Fe Modelling ◽  
Flexible Wall ◽  
Sensitive Clay

A finite-element (FE) numerical study using PLAXIS-3D software was carried out to reproduce and validate a full-scale experimental in situ test and to investigate the earth pressure on a flexible temporary trench box shield in soft and sensitive clay soil. The excavation trench model was 6 m (20 ft) deep and was considered as nonlinear and anisotropic clay. A 45 kPa (0.94 ksf) surface overload on top of the soil near the trench box was also simulated to produce a maximum load case on the flexible wall of the shield. Both Mohr-Coulomb (MC) and hardening soil (HS) constitutive soil models were considered for FE analysis. Different values of the modulus reduction factor (MRF) and the coefficient of earth pressure at rest ( K 0 ) were considered to validate the model. For a specific shear strength profile, FE analysis with a linear elastoplastic soil model showed relatively small differences in soil pressure with the field test results along the depth of the trench. Results were also compared with the predictions of well-established analytical formulae.

scholarly journals Soil-Structure Interaction of Flexible Temporary Trench Box: Parametric Studies Using 3D FE Modelling

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Miah Alam ◽  
Omar Chaallal ◽  
Bertrand Galy
Keyword(s):  
Finite Element ◽  
Plate Thickness ◽  
Earth Pressure ◽  
Material Model ◽  
Computer Code ◽  
Soil Pressure ◽  
Fe Modelling ◽  
Deep Trench ◽  
Constitutive Material Model ◽  
Sensitive Clay

This paper presents the results of two parametric finite-element studies that were carried out using the PLAXIS-3D finite element (FE) computer code. The following objectives and corresponding parameters were considered: (i) to evaluate the soil pressure on the steel trench box shield; the parameters studied were related to soil type and material, and the study considered till, dry sand, wet sand, and sensitive clay soil; (ii) to assess the effect of trench box material and geometry on earth pressure; the parameters studied were related to trench box material (steel versus aluminum) as well as geometry (plate thickness and strut diameter). These studies included simulation of two steel (or aluminum) trench box shields stacked upon each other to cover the total 6 m (20 ft) deep trench. A Mohr-Coulomb (MC) constitutive material model was chosen for FE analysis (FEA). The FEA results were compared to empirical apparent earth pressure diagrams for a sensitive clay. Comparisons showed that the parameters related to the soil and the trench box have a significant influence on earth pressures.

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