Liquefaction Susceptibility in the Northern Provinces of Thailand

Abstract

Problem statement: There are quite a few active faults recently found in the western and northern parts of Thailand, which could possibly induce earthquakes of magnitude (M L ) of 5.5-6.5. Although seismic design code has been enforced in the area since 1980, the fundamental knowledge on dynamic soil behavior has not been extensively attained. Approach: Collection of existing borehole information in the targeted areas to form a typical subsoil profile. This borehole information, together with analytical result obtained from logistic regression based on worldwide liquefaction database was used to conduct an effective stress analysis. Result: Literature reviews of the existing boreholes from the two largest provinces in the north, Chiang-Mai and Chiang-Rai, revealed that the areas were underlain by layers of loose to medium dense sand found at shallow depths. The corrected SPT Nvalue of those sand layers varies in the range of 5-20. A simple tool correlating the liquefaction probability, which correlated excess pore water pressure and peak ground acceleration, was proposed for the studied areas. Conclusion: The proposed correlation provided preliminary tool to evaluate risk of the shallow foundation from partial liquefaction in the two northern provinces of Thailand.