Evaluation of liquefaction potential using cone penetration test (CPT) and standard penetration test (SPT)

Abstract

To evaluate soil resistance against liquefaction, a simplified procedure has been developed based on directly field soil testing. There are four recommended field tests, including CPT and SPT. Soil resistance to liquefaction is measured by the safety factor SF, which is the ratio between the capacity of the soil to resist liquefaction cyclic resistance ratio (CRR) and the soil stress occurs due to an earthquake cyclic stress ratio (CSR). If SF <1, liquefaction occurs. This research was carried out at Sanur area, Southeast Denpasar City, Bali, by conducting 6 pairs of CPT and SPT tests, each of 6-meter depth. The Ground Water Level (GWL) at this area is 1.5 meter below the soil surface. The soil type is silty sand to sandy silt, with the unit weight between 1.617 to 1.837 g/cm^3. The calculation results, both with CPT and SPT, show that the soil layer did not experience liquefaction with earthquake magnitude Mw = 4.0. At Mw = 5.0, liquefaction occurs in most soil layers, except the 1.5-meter upper soil layer. On Mw = 6.0, almost all soil layers experience liquefaction. Evaluation of soil resistance to liquefaction using CPT and SPT gives results that are not much different.