71 Advances in analysis of soil liquefaction during earthquakes

Abstract

This chapter focuses on the advances in analysis of soil liquefaction during earthquakes. Soil liquefaction has caused major damage during past earthquakes. Based on laboratory experiments on saturated soil specimens, soil liquefaction was understood to be the result of an increase in pore water pressure associated with a decrease in soil frictional resistance during earthquake shakings. The engineering understanding of soil liquefaction during earthquakes is based largely on case histories of liquefaction occurrence and related ground deformation, documented from past earthquakes. In geotechnical earthquake engineering practice, liquefaction-induced ground deformations are usually estimated using three different types of empirical models that predict separately (1) the occurrence of liquefaction, (2) ground settlement, and (3) lateral ground deformation. Soil liquefaction has been investigated successfully in great depth by means of physical models using specimens in the laboratory and reduced-scale models in shaking tables and centrifuges. Many numerical models have been proposed for simulating soil liquefaction. They fall into two main categories: (1) simplified when they simulate only a few particular aspects of soil liquefaction for practical engineering applications, and (2) generalized when they attempt to account for a large number of soil liquefaction features. There are two recent developments in soil liquefaction: soil liquefaction as a material instability, and computer simulations with discrete element methods.