Assessment of liquefaction potential for a silty sand in Central Western Taiwan

Abstract

The Chi Chi earthquake of September 21, 1999 triggered extensive soil liquefaction in silty sand deposits in Central Western Taiwan. The post Chi Chi earthquake studies indicated that the fines content adjustments according to the simplified procedure could cause rather inconsistent results amongst various assessment methods. The authors performed a series of cone penetration chamber calibration tests and cyclic triaxial tests on remolded Mai Liao Sand (MLS) specimens, with various fines contents and densities. The triaxial cell was equipped with bender elements and shear wave velocity (V-s) was measured prior to the cyclic shearing test. With these data, the authors were able to calibrate the correlations among CRR, cone tip resistance (q(c)) and V-s for MLS. A test site was developed in Yuan Lin County where standard penetration test (SPT), seismic piezocone and field V-s measurements were performed and low disturbance silty sand samples using a Laval sampler were taken. A series of cyclic triaxial tests were conducted on the Laval samples with V-s measurements using bender elements. These field and laboratory test results were used to validate the correlations among CRR, q(c), and V-s from calibration tests and the simplified procedure typically used in liquefaction potential assessment. This paper describes the laboratory calibration tests on MLS, results from Yuan Lin test site studies and discusses their implications in the assessment of liquefaction potential for the silty sand in this region.