New method for calculating probability of sand liquefaction

Based on the demand of developing liquefaction prevention and control technology under the concept of risk, a new univariate-based (UB) probability method is deduced, and a new formula is proposed, which takes the in-situ standard penetration blow count as the main control parameter, and the verification of the new method is conducted by using the recent actually measured data. The results shows that through the combination of the mature deterministic method of liquefaction discrimination with the classical mathematical method for the probability can solve the deviation problem of the evaluation method which is completely dependent on sample regression or learning caused by the incompleteness of the current measured data, and can also overcome the unreasonable disadvantages of the existing evaluation methods for liquefaction probability caused by the CSR theory when the buried depth of sand layer exceeds 10 m. The reliability and advancement of the new method and formula are verified by 341 groups of measured liquefaction data with PGA range of 0.23g to 0.89g and buried depth of 2 to 30 m from the 2011 New Zealand Earthquake. The proposed formula has been adopted in the revised version of the General Rule for Performance-Based Seismic Design of Buildings of China, which can provide guidance and technical support for the related specification revision and engineering application, and the proposed univariate-based approach for probability calculation can be used as a guide and reference for probability calculation of dichotomies with multiple independent variables.