Centrifuge Modeling of Earthquake-Induced Lateral Spreading in Sand

This paper presents results of 11 centrifuge model tests of liquefaction and earthquake-induced lateral spreading in sand using a laminar box. The centrifuge experiments simulate a horizontal or sloping, 10-m thick stratum of water-saturated homogeneous coarse sand of infinite lateral extent and relative density 40–45%, placed on an impervious rigid base. Such homogeneous, clean, coarse stratum represents some field liquefaction situations, but not others involving fine and/or silty sands or strong layering of strata of different permeabilities. The centrifuge tests presented provide significant general insight into mechanisms and parameters influencing the lateral spreading phenomenon. The layer was subjected to lateral base shaking with a prototype peak acceleration ranging from 0.17 to 0.46g, a frequency of 1–2 Hz, and a duration of approximately 22 cycles in all cases. The slope angle simulated in the field α_field ranged from 0 to 10°. Detailed discussions and comparisons of the 11 centrifuge test results are included. The observed effects of prototype slope angle α_field, input peak acceleration, a_max, and frequency f on the following measured parameters are summarized: excess pore pressure u, thickness of liquefied soil H_l, soil acceleration a, lateral displacement D_H, permanent shear strain γ, and surface settlement S. It is found that if H_l is considered, D_H depends only on α_field and H_l, with no influence of a_max and f. System identification analysis of the shear stress–strain response reveals significant dilative behavior of the liquefied soil at large cyclic downslope strains, characterized by large acceleration and strength increases and simultaneous pore pressure drops that arrest the downslope lateral displacement.