Evaluation of Liquefaction Potential Index in the Educational Infrastructure Reconstruction Project at the University of Tadulako, Palu City, Central Sulawesi

Abstract

On September 28, 2018, The Palu-Koro fault triggered an earthquake of Mw 7.5. at a depth of 20 km and 72 km northeast of Palu City. As a result, the University of Tadulako suffered significant damage post this earthquake. The Ministry of Public Works and Housing was assigned to reconstruct this location, which was located near the epicentre, and there are alluvium deposits of the Holocene age with loose sand soil and shallow groundwater levels on-site. Based on the Indonesian Seismic Code SNI 1726:2019, it is necessary to propose liquefaction potential and mitigation for building planning. The study aims to calculate the Safety Factor (S.F.) against liquefaction using a simplified procedure by Seed-Idriss and developed methods by Idriss-Boulanger. The S.F. was used as an input to determine the Liquefaction Potential Index (LPI) by Iwasaki et al. The study showed different categories of LPI values. The highest LPI value was found at BH-05, with a very high liquefaction potential. The soil depths susceptible to liquefaction are up to 9 meters. Application of deep foundation penetrating liquefiable soil layer is recommended as the mitigation. It is necessary to conduct further studies on the deep foundation analysis to be applied to this location.