Multi-scale simulation of wave propagation and liquefaction in a one-dimensional soil column: hybrid DEM and finite-difference procedure

The paper describes a multi-phase, multi-scale rational method for modeling and predicting free-field wave propagation and the weakening and liquefaction of near-surface soils. The one-dimensional time-domain model of a soil column uses the discrete element method (DEM) to track stress and strain within a series of representative volume elements (RVEs), driven by seismic rock displacements at the column base. The RVE interactions are accomplished with a time-stepping finite-difference algorithm. The method applies Darcy's principle to resolve the momentum transfer between a soil's solid matrix and its interstitial pore fluid. Different algorithms are described for the dynamic period of seismic shaking and for the post-shaking consolidation period. The method can analyze numerous conditions and phenomena, including site-specific amplification, down-slope movement of sloping ground, dissolution or cavitation of air in the pore fluid, and drainage that is concurrent with shaking. Several refinements of the DEM are described for realistically simulating soil behavior and for solving a range of propagation and liquefaction factors, including the poromechanic stiffness of the pore fluid and the pressure-dependent drained stiffness of the grain matrix. The model is applied to four sets of well-documented centrifuge studies. The verification results are favorable and highlight the importance of the pore fluid conditions, such as the amount of dissolved air within the pore water.

Automated summary

The paper presents a multi-phase, multi-scale rational method for modeling and predicting free-field wave propagation and the weakening and liquefaction of near-surface soils using the discrete element method (DEM). The method involves analyzing various conditions and phenomena related to seismic shaking and post-shaking consolidation period, as well as refining the DEM for realistically simulating soil behavior and solving propagation and liquefaction factors.