Verification and validation of two-phase material point method simulation of pore water pressure rise and dissipation in earthquakes

Traditional numerical methods, such as the finite element method or the finite difference method, are generally used to analyze the slope response in the pre-failure and failure stages. The post-failure phase is often ignored due to the unsuitability of these methods for dealing with problems involving large deformations. However, an adequate analysis of this latter stage and a reliable prediction of the landslide kinematics after failure are very useful for minimizing the risk of catastrophic damage. This is generally the case of the landslides triggered by an excess in pore water pressure, which are often characterized by high velocity and long run-out distance. In the present paper, the deformation processes occurring in an ideal slope owing to an increase in pore water pressure are analyzed using the material point method (MPM) that is a numerical technique capable of overcoming the limitations of the above-mentioned traditional methods. In particular, this study is aimed to investigate the influence of the main involved parameters on the development of a slip surface within the slope, and on the kinematics of the consequent landslide. The obtained results show that, among these parameters, the excess water pressure exerts the major influence on the slope response. A simple equation is also proposed for a preliminary evaluation of the run-out distance of the displaced soil mass.

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An Investigation of Rainfall-Induced Landslides From the Pre-Failure Stage to the Post-Failure Stage Using the Material Point Method

Frontiers in Earth Science ◽

10.3389/feart.2021.764393 ◽

2021 ◽

Vol 9 ◽

Author(s):

Wei-Lin Lee ◽

Mario Martinelli ◽

Chjeng-Lun Shieh

Keyword(s):

Numerical Model ◽

Pore Water ◽

Numerical Solutions ◽

Pore Water Pressure ◽

Water Pressure ◽

Material Point Method ◽

Material Point ◽

Point Method ◽

Failure Behavior ◽

Clear Understanding

The kinematic behavior of rainfall-induced landslides from the pre-failure stage to post-failure stage contains important information for risk assessment and management. Because a complex relationship exists between rainfall conditions, pore water pressure, soil strength, and movement rates, a numerical model is the most efficient way to investigate the behavior of rainfall-induced landslides. In this study, the material point method (MPM) is used to investigate the dynamic behavior of landslides. First, the rainfall boundary conditions are extensively verified by comparing 1-D consolidation tests against other numerical solutions. Then, a numerical model is used to simulate a lab-scale rainfall-induced slope failure. A parametric study shows the influence of rainfall intensity on pore water pressure development, failure triggering time, surface displacement, and velocity. The use of the MPM provides a clear understanding in the failure mechanism and post-failure behavior of a rainfall-induced landslide.

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