Identification of liquefaction potential using empirical and numerical approach on Maranatha Area, Sigi Regency

¹ Department of Civil and Environmental Engineering, Universitas Gadjah Mada, Bulaksumur,Yogyakarta, Indonesia
² BWS Nusa Tenggara II, Ministry of Public Works and Housing Indonesia, Jl. Frans Seda Bundaran PU, Kupang, Indonesia

^* Corresponding author: ahmad.rifai@ugm.ac.id

Abstract

A Liquefaction that hit Palu City and Sigi Regency, Central Sulawesi on September 28th, 2018 triggered by a 7.5 magnitude earthquake has been stated as National Disaster by BNPB. This paper aims to identify the liquefaction potential considering the soil structure, N-SPT data, seismic history, water level conditions, and relevant geotechnical data at Maranatha Area. This Village located very close to the liquefaction occurance mentioned above is chosen as the main focus location of this research. The research focused on Maranatha section of Gumbasa Irrigation Rehabilitation Project-3rd Package. Eight selected locations along the project are analyzed using the Simplified Method to identify the liquefaction potential. Based on geotechnical investigation found that the soil conditions of some areas are cohesionless. Soil exploration shows that most soil deposit consists of sandy and clay layers from the ground surface up to a depth of 20,00 meters, and a high elevation of groundwater level (-2.10 to -9.00). The potential analysis of liquefaction based on numerical approach empowers the empirical approach which indicates that among 8 boreholes, 3 of them were quite potential for liquefaction to occur and Borehole-37 was to be on concern due to its potential for flow liquefaction. It is found that certain depths of soil layers of the areas are prone to liquefaction with Potential Index of 1.70 to 10.55 (Low to High Potential).