Numerical modelling of sand liquefaction via a weakly coupled approach between lattice spring and discrete element methods

Liquefaction, often induced by seismic activities, poses considerable risk to structures and necessitates accurate prediction and analysis to enhance engineering designs. By adopting a weakly coupled method, this research synergizes the benefits of both discontinuum and continuum frameworks to assess liquefaction mitigation strategies in practical engineering scenarios. Using the Distinct Lattice Spring Model (DLSM), three-dimensional engineering scale models were developed. The liquefaction process in saturated soils was governed by the Drucker-Prager and Finn models. The DEM (Discrete Element Method) was utilized to simulate the liquefaction mechanism, aiding in deriving the Finn model parameters. This process involved establishing a quantitative link between the soil's elastic modulus, Poisson's ratio, initial pressure, and the liquefaction parameter. The validity of the proposed approaches was confirmed through comparisons with physical experiments. The study also delved into the quantitative analysis and evaluation of liquefaction and deformation control efficacy in foundations of one real engineering application, considering various geometric designs of diaphragm walls. Findings indicate that a grid-like diaphragm wall significantly mitigates liquefaction risks from seismic waves in multiple directions. An optimal outcome was suggested with a spacing of 54 m between reinforced diaphragm walls. The developed numerical approach offers a new tool for the analysis of liquefaction risks.