Numerical investigation of liquefaction susceptibility of sands considering fabric effects

Natural soil deposits may possess a highly anisotropic nature. The fabric anisotropy of soils which is induced during the soil formation process can lead to severe variation in field scale responses. Although the influence of fabric on the response of sands is well known and several advanced constitutive models have been developed to account for...

Periodic random fields to perform site response and liquefaction susceptibility analysis

Free-field site response analysis is a standard technique used to predict soil deposit dynamic response and liquefaction susceptibility. Such analyses are typically carried out by implementing periodic boundaries to guarantee the same speed of the dynamic waves travelling across them. However, when using random fields to consider the impact of...

Implementing Dynamic Boundary Conditions with the Material Point Method

The material point method (MPM) is gaining an increasing amount of attention due to its capacity to solve geotechnical problems involving large deformations. Large deformations in geotechnics usually involve the failure process and therefore dynamic analyses are often carried out. However, simulating the (infinite) continuous domain using...

Liquefaction Assessment and Soil Spatial Variation

Soil liquefaction is investigated considering a saturated soil deposit and by implementing standard techniques of random field theory to distribute initial void ratio values and assess liquefaction risk. The soil domain is represented in a 2-dimensional (2D) random finite element model for the dynamic analysis of coupled behavior. Multiple...

Comparison of 1D and 2D liquefaction assessment methods considering soil spatial variability

1D soil column techniques are widely used to evaluate the potential of liquefaction in a system of soil layers. This approach generally leads to large inaccuracies since (1) soil layers are hardly homogeneous and perfectly horizontal and (2) horizontal effects are neglected. To demonstrate the limitation of 1D strategies and the need for 2D...

Study of landslides and soil-structure interaction problems using the implicit material point method

Mesh based methods such as the finite element method (FEM) are the most usually used techniques for analysing soil-structure interaction problems in geotechnical engineering. Nevertheless, standard FEM is unable to simulate large deformations and contact, hindering the realistic simulation of rotational, sliding, pull-out and overturning...

Development of an implicit contact technique for the material point method

An implicit contact algorithm for the material point method (MPM) has been developed to simulate contact. This allows recently developed implicit MPM codes to simulate large-scale deformations and interaction with external bodies. The performance of the method has been investigated and compared to an existing explicit method using benchmark...

Development of a Robust Coupled Material Point Method

The material point method (MPM) shows promise for the simulation of large deformations in history-dependent materials such as soils. However, in general, it suffers from oscillations and inaccuracies due to its use of numerical integration and stress recovery at non-ideal locations. The development of a hydro-mechanical model, which does not...

On stress oscillation in MPM simulations involving one or two phases

Stress oscillations in the material point method (MPM) are one of the major reasons unrealistic results are obtained. In this paper an investigation of the stress oscillations occurring when using one- and two-phase approaches is performed. Specifically, an axisymmetric benchmark and a two-dimensional plane strain problem are used to demonstrate...

An investigation of stress inaccuracies and proposed solution in the material point method

Stress inaccuracies (oscillations) are one of the main problems in the material point method (MPM), especially when advanced constitutive models are used. The origins of such oscillations are a combination of poor force and stiffness integration, stress recovery inaccuracies, and cell crossing problems. These are caused mainly by the use of...

The use of MPM to estimate the behaviour of rigid structures during landslides

In geotechnical engineering, proper design of retaining structures is of great importance, since failure of these structures can lead to catastrophic consequences. Nowadays, the finite element method is seen as a reliable numerical technique to analyze soil behaviour and is widely used to assess the interaction be-tween soil and rigid structures...

Compound material point method (CMPM) to improve stress recovery for quasi-static problems

Stress oscillations and inaccuracies are commonly reported in the material point method (MPM). This paper investigates the causes and presents a method to reduce them. The oscillations are shown to result from, at least in part, two distinctly different causes, both originating from the shape function approximations used. The first is due to the...

An evaluation of MPM, GIMP and CMPM in geotechnical problems considering large deformations

Stress oscillations are a common phenomenon in the material point method (MPM), since this numerical method typically uses regular finite element (FE) shape functions to map variables from surrounding nodes to material points and vice versa, independently of the locations of the material points within an element. In integration this leads to a...