Liquefaction Ground Deformation Predicted from Laboratory Tests

A laboratory based approach is described to obtain the post-liquefaction steady-state shear strength of very loose, recently deposited, layered fluvial silty sand deposits susceptible to lateral spreading. Triaxial specimens are formed by the Remolded Discontinuously Vet Pluvial Soil Sample (RDVPSS preparation method. RDWPSS silty sand specimens are prepared by dumping the soil in water and a lowing for segregation and development of layers. Ten undrained tests were conducted using ranges of consolidation pressures σ̅3c = 0.2 to 2.7 kg/cm2 and Kc = σ̅1c/ σ̅3c = 1 to 2. The experiments included both monotonic compression triaxial (C̅I̅U̅) and cyclic torsional (CyT-C̅A̅U̅) tests. The RDWPSS soil was contractive in all tests including those conducted at the lowest confining pressures. Unique steady-state lines are defined from the results of these tests. The ratio Sus/ σ̅1c is constant and equal to about 0.12 for Kc = 1 to 1.5, and it is proposed us c to use this value for lateral spread evaluations in conjunction with Newmark\u27s sliding block analysis to predict permanent displacement. Finally, the approach is successfully used in a preliminary evaluation of the 18 cm lateral displacement measured at the Wildlife site in Southern California after the November 27, 1987 earthquake