This report describes the results of a detailed investigation of improved procedures for evaluation of liquefaction hazards in Washington State, and describes the development and use of a computer program, WSliq, that allows rapid and convenient performance of improved analyses.
The report introduces performance-based earthquake engineering (PBEE) concepts to liquefaction hazard evaluation. PBEE procedures have been developed and implemented for evaluation of liquefaction potential, lateral spreading displacement, and post-liquefaction settlement. A new model for estimation of the residual strength of liquefied soil was also developed.
The WSliq code was developed to have broad capabilities for evaluation of liquefaction susceptibility, liquefaction potential, and the effects of liquefaction. It provides new methods for dealing with the magnitude-dependence inherent in current procedures, and makes the common “magnitude selection” problem moot via a new multiple-scenario approach and through the use of PBEE procedures.