CPT-based liquefaction analysis, Part 1: Determination of limit state function

This paper is the first of a set of two papers that address the issue of ea rthquake-induced liquefaction potential. In this paper, a CPT-based limit s tate function for assessing the cyclic liquefaction resistance of sandy soi ls is presented, The Liquefaction resistance of a soil is generally express ed as cyclic resistance ratio (CRR), while the seismic load that causes liq uefaction is expressed as cyclic stress ratio (CSR), By definition, CRR is equal to the maximum CSR that a soil can sustain without the occurrence of cyclic liquefaction, In the present study, a new method to establish a limi t state function for evaluating cyclic liquefaction resistance is developed . This new method is based on an artificial neural network (ANN) modelling and analysis of 225 field liquefaction performance records. First, an ANN m odel is developed to predict the occurrence of liquefaction based on histor ic field performance records. Second, a search procedure is developed to lo cate data points on the limit state surface. Third, another ANN model is cr eated to approximate the multi-variable limit state function, The establish ed approximate function, an ANN model, can be used to determine the CRR of a soil using CPT data. The developed CPT-based Limit state function forms t he basis for the development of a risk-based method for assessing, cyclic l iquefaction potential.