Engineering evaluation of permanent ground deformations due to seismically-induced liquefaction

ABSTRACT

A study is presented on the engineering evaluation of permanent lateral ground deformation associated with liquefaction and lateral spreading during earthquakes. Newmark's rigid sliding block model is used as main analytical technique, based on the reasonable assumption that generally the deformation occurs during shaking in the downhill direction of the ground surface slope. The study involves laboratory tests, analitical work, and comparisons with case histories and field observations. It culminates with a simplified method to predict lateral deformation using regional attenuation relations for peak ground acceleration and velocity. The laboratory work includes two series of tests. In the first series, drained and undrained cyclic triaxial experiments at different frecuencies on clean, medium dense Ottawa sand were used test a basic assumption of Newmak's method. It is concluded that the method can be applied to dry sand but not to saturated medium dense sand, due to their dilative character and to the shape of their dense stress-strain curves, which do not exhibit the strenght plateau required by the method(AU)