Some Aspects of the Impact of Multidirectional Shaking on Liquefaction of Level and Sloping Granular Deposits

Abstract

A very limited number of computational studies have been presented for the analysis of the response of saturated granular soils to multidirectional shaking despite it being the realistic mode of loading that resembles an actual earthquake. Herein, this paper examines the capabilities of a recently developed, coupled lattice Boltzmann method (LBM)–discrete element method (DEM) of modeling level and gently sloped soil deposits when subjected to bidirectional shaking. The results of conducted simulations show that bidirectional shaking may increase surface settlement of level deposits by about 30% over unilateral shaking. The depth along the deposit that experiences excess pore pressure ratio close to unity increases as a result of bidirectional shaking compared to unilateral shaking. Bidirectional shaking also increases the magnitude of lateral spreading and associated shear strains in sloping deposits. Other aspects of the response include capturing soil dilative behavior and associated temporary increase in soil strength during liquefaction. The increase in soil strength was more pronounced in the case of the sloping deposit. Investigation into fabric evolution during shaking indicates that soil dilation increases the level of anisotropy and the degree of anisotropy postliquefaction increases compared to the preshaking state.