Liquefaction Potential Analysis and Mitigation at the Sediment Control Structures on Bangga River, Central Sulawesi

Abstract

The Palu Earthquake in 2018 has triggered a debris flow incident in Bangga River. As a form of protection for similar disasters, it is planned to construct Sediment Control Structures in the Bangga River. The Bangga River area also has liquefaction potential that needs to be considered to ensure the structure's stability. This study aims to perform liquefaction analysis at the Sediment Control Structure area. Liquefaction potential is calculated using the Simplified Method and Liquefaction Potential Index Method based on 15 bore-log data that includes SPT. Further analysis is conducted by calculating lateral spreading and settlement potential. Liquefaction potential is found in the Consolidation Dam area, leading to lateral spreading and settlement at the footing of the structure. The lateral spreading potential is found from a depth of 11 to 13 m, with the potential movement of 0.886 m and located only 1 m below the Consolidation Dam foundation. Mitigation planning is proposed by compaction method to increase the liquefaction resistance. The safety against liquefaction is achieved by increasing NSPT value of the vulnerable soil to be greater than 36. This increasing soil strength can reduce lateral spreading potential up to 95% and the settlement potential up to 89%.