Lagrangian modelling of large deformation induced by progressive failure of sensitive clays with elastoviscoplasticity

Abstract

International audienceThis paper presents a Lagrangian formulation of elastoviscoplasticity, based on the Particle Finite Element Method, for progressive failure analysis of sensitive clays. The sensitive clay is represented by an elastoviscoplastic model which is a mixture of the Bingham model, for describing rheological behaviour, and the Tresca model with strain softening for capturing the progressive failure behaviour. The finite element formulation for the incremental elastoviscoplastic analysis is reformulated, through the application of the Hellinger-Reissner variational theorem, as an equivalent optimization program that can be solved efficiently using modern algorithms such as the interior-point method. The recast formulation is then incorporated into the framework of the Particle Finite Element Method for investigating progressive failure problems related to sensitive clays, such as the collapse of a sensitive clay column and the retrogressive failure of a slope in sensitive clays, where extremely large deformation occurs

An edge‐based strain smoothing particle finite element method for large deformation problems in geotechnical engineering

“…For soft sensitive clay, the following parameters according to Zhang et al are adopted in the simulation: Young's modulus E = 1 × 10 3 kPa, friction angle φ = 0° assuming undrained shear strength fully taking by the cohesion, dilatancy angle ψ = 0°, peak cohesion c p = 22 kPa, residual cohesion c r = 1.2 kPa, and shape factor η = 5, which is approximately equivalent to the value of linear reduction relationship adopted by Zhang et al and Wang et al. The soil density is ρ = 1.7 × 10 3 kg/m 3 .…”

“…The final configuration of the slope, shown in Figure I, indicates that most of the clay involved in collapses has been remoulded. Eventually, the retrogressive failure results in a deposit with a run‐out distance of 22.49 m and a retrogression distance of 18.61 m, which is reasonable according to the parametric study of Zhang et al . Note that the run‐out and retrogression distances are affected by the model parameters, the interface friction coefficient, and even the adopted constitutive model.…”

Dynamic modelling of retrogressive landslides with emphasis on the role of clay sensitivity

“…The neglect of the rheological property of sensitive clays, for example the viscosity, has an adverse effect on the correct prediction of landslides in sensitive clays, particularly for clays of high sensitivity that behave more like liquids after they are fully remoulded. More recently, a Lagrangian formulation of elastoviscoplasticity was proposed in Zhang et al for analysing large deformation problems related to sensitive clays. In the formulation, the elastoviscoplastic model, which is a mixture of Tresca model with strain softening and the classical Bingham model, was used to describe the complex behaviour of sensitive clays.…”

“…To tackle the issues related to the extreme change of geometry, for example mesh distortion and free‐surface evolutions, the model was implemented into the framework of the particle finite element method . It has been shown in Zhang et al that this approach is capable of simulating progressive failure of geostructures in sensitive clays with a typical example being the collapse of a column of sensitive clay. Moreover, its effectiveness and robustness in simulating landslides in sensitive clays have been illustrated as well in Zhang et al…”

“…It has been shown in Zhang et al that this approach is capable of simulating progressive failure of geostructures in sensitive clays with a typical example being the collapse of a column of sensitive clay. Moreover, its effectiveness and robustness in simulating landslides in sensitive clays have been illustrated as well in Zhang et al…”