Liquefaction resistance of sands in the Northern part of Thailand

Abstract

The northern part of Thailand is located in low to medium seismic risk zones. There are a few active faults recently found in the western and northern parts of the country. These could possibly induce earthquakes of magnitude (ML) 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. Literature reviews of the existing boreholes from the two largest provinces in the north, including Chiang Mai and Chiang Rai, revealed that the areas are underlain by loose to medium dense sand layers found at shallow depths. The corrected SPT N-value of those sand layers varies in the range of 5-20 blows/ft. These borehole information, together with the result obtained from the logistic regression based on worldwide liquefaction database are used to conduct the effective stress analysis. A simple tool correlating the liquefaction probability, estimated excess pore water pressure and peak ground acceleration is proposed. Preliminary risk zones in these two provinces were identified.