Liquefaction Susceptibility in the Northern Provinces of Thailand

Nasser Nasser

doi:10.3844/ajeassp.2009.194.201

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 (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. 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 N-value 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.

Highlights

INTRODUCTIONThere are quite a few moderate earthquakes being felt (Table 1) in Thailand
Not until recently that Thailand becomes aware of the threats from earthquakes
The most common set of physical variables adopted in several liquefaction studies is the Cyclic Stress Ratio (CSR) and the corrected SPT resistance

Summary

INTRODUCTION

There are quite a few moderate earthquakes being felt (Table 1) in Thailand Epicenters of those recent medium earthquakes were located in the northern and western parts of the country. Warnitchai and Lisantono[1] formulated a database containing instrumental data of earthquakes from 1910-. They indicated that earthquakes of magnitude (ML) of 6.5 with maximum ground acceleration of 0.2g may occur in the northern and western parts of Thailand (Fig. 1). Its existence initially infers certain levels of liquefaction risk. This has been further confirmed by evidence showing trace of liquefaction (Fig. 3) found from a trench exploration in the area. Probabilistic study and dynamic analytical results is used as a primary tool for detail evaluation

MATERIALS AND METHODS

RESULTS AND DISCUSSION

9.5-38.5 Plastic dilatancy Overall dilatancy s1

CONCLUSION