Introduction and Application of a Simple Probabilistic Liquefaction Hazard Analysis Program: HAZ45PL Module

Abstract

The 2016 Meinong Earthquake hit southern Taiwan and many shallow foundation structures were damaged due to soil liquefaction. In response, the government initiated an investigation project to construct liquefaction potential maps for metropolitans in Taiwan. These maps were used for the preliminary safety assessment of infrastructures or buildings. However, the constructed liquefaction potential map used the pseudo-probabilistic approach, which has inconsistent return period. To solve the inconsistency, the probabilistic liquefaction hazard analysis (PLHA) was introduced. However, due to its complicated calculation procedure, PLHA is not easy and convenient for engineers to use without a specialized program, such as in Taiwan. Therefore, PLHA is not a popular liquefaction evaluation procedure in practice. This study presents a simple PLHA program, HAZ45PL Module, customized for Taiwan. Sites in Tainan City and Yuanlin City are evaluated using the HAZ45PL Module to obtain the hazard curve and to construct the liquefaction probability map. The liquefaction probability map provides probabilities of different liquefaction potential levels for engineers or owners to assess the performance of an infrastructure or to design a mitigation plan.

A Review of Probabilistic Approaches for Assessing the Liquefaction Hazard in Urban Areas

“…Then a PLTA or PLMSA approach is used to estimate the liquefaction RP in a region, as shown in Kramer and Mayfield [35]. PLHA is framed into a PBEE framework to incorporate the occurrence of the ground motion (PGA and M w pairs) obtained from PSHA into the calculation of a liquefaction triggering or manifestation approach [125]. The PBEE framework allows to incorporate contributions from all hazard levels into a performance evaluation to compute an RP for liquefaction-triggering [44].…”

“…However, these methods require accurate and reliable data, and expert knowledge in statistics and geotechnical engineering to properly apply and interpret the results. Therefore, PLHA is not a popular liquefaction evaluation procedure in the practice [125].…”

“…Without liquefaction case history data to develop Groningen-specific thresholds, the thresholds proposed by Iwasaki et al [69] for the LPI framework were conservatively used in this study with the LPI ISH framework i.e. : LPI ISH < 5: no to minor surficial liquefaction manifestations, 5 ≤ LPI ISH ≤ 15: moderate surficial liquefaction manifestations, LPI ISH > 15: severe surficial liquefaction manifestations • PLHA was performed using a Monte Carlo method, in which probability distributions for seismic activity rates, event locations and magnitudes, and the resulting ground motions were sampled Geyin & Maurer [67] PLTA or PLMSA-based approach or liquefaction deterministic assessment (LDA) based approach • PLMS Advantages, criteria, and limitations • The application of the Geyin and Maurer [67] PLMA approach was demonstrated by predicting the return period of liquefaction manifestations in the South-of-Downtown (SODO) district of Seattle (USA), wherein predictions are compared to historical observations • For the PLMSA approach were used the fragility functions developed in the same study Chou et al [125] PLTA or PLMSA-based approach or liquefaction deterministic assessment (LDA) based approach • LDA Advantages, criteria, and limitations • This study presented the HAZ45PL Module. This module served to obtain the hazard curve and to construct the liquefaction probability map for sites in Tainan and Yuanlin City.…”