Statistically determining liquefaction potential index (LPI)-based liquefaction potential classification for the practice in Taiwan

Abstract

In geotechnical earthquake engineering, the liquefaction potential index (LPI) proposed by Iwasaki et al. (1982) is commonly adopted to quantify the severity of ground manifestation or the damage to low-rise buildings due to soil liquefaction. Iwasaki et al. (1982) also recommended an LPI-based classification for assessing liquefaction risks, which is prevalent in seismic design and liquefaction hazard map generation in Taiwan; however, this classification was derived from the Japan case histories along with the Japanese Road Bridge Design Code calculation procedure, such that its consistency to Taiwan sites and assessing methods in Taiwan seismic design codes remains unknown. To examine its consistency to Taiwan sites and determine the classification for the practice in Taiwan, this paper exploits the liquefied and non-liquefied case histories of the 1999 Chi-Chi earthquake and those of the 2016 Meinong earthquake in Taiwan to evaluate their LPI values by 4 SPT-based simplified methods which are suggested in Taiwan seismic design codes for the ordinary buildings and statistically characterizes the distributions of those LPI values. The characterization results are compared with the classification suggested by Iwasaki et al. (1982), and utilized to determine a new LPI-based liquefaction potential classification, which is believed as a reference for seismic design and liquefaction potential map generation in Taiwan.