Mitigation plan against liquefaction potential on Gumbasa Irrigation Canal around Jono Oge area after 2018 Central Sulawesi Earthquake

Abstract

Gumbasa Irrigation Area was one of the public infrastructures affected by the liquefaction and flow-slide. Restoring it to operate as before required a reconstruction plan with consideration on potential damage caused by the earthquake and liquefaction. The objective of this study was to assess the performance of the mitigation plan applied on Gumbasa Irrigation Area (canal and rice field). Two mitigation plans to be applied in the Gumbasa Irrigation Canal are evaluated, i.e., (1) implementing impermeable lining and geogrid; (2) applying impermeable lining and steel-sheet pile with drain. Each mitigation plan was compared using the finite element method to examine the stability and displacement mechanism. Based on the result, the first mitigation plan was identified as more effective to reduce displacement caused by earthquake and liquefaction potential. The lowering groundwater method was applied on Jono Oge rice fields area by maintaining the recommended groundwater level obtained from the simulation of groundwater level using the simplified method. We concluded that mitigation plans on irrigation canal by applying impermeable lining and geogrid and by lowering groundwater on the rice fields area were the best mitigation plan for Gumbasa Irrigation Area.

Relief well as liquefaction mitigation option in Mpanau, Sigi, Central Sulawesi, Indonesia

“…A pressure relief well (or drain) that provides quick removal of excess water pressure buildup. Several case studies have demonstrated the success of this type of drainage using gravel columns or vertical geocomposite drainage with relatively large diameters [8]. It has also been used to prevent "blowout" where the water pressure and vertical outflow gradient can become high, and has been incorporated in the design of flood control embankments, as in the Ejecta Potential theory which is related to the Artesian Flow Potential [11].…”

“…Liquefaction mitigation has been discussed by several studies on the Gumbasa Canal, one of which is the use of impermeable layers [8]. Meanwhile, the influence of aquifers on liquefaction is hypothesized based on oral sources immediately after the earthquake [9].…”

“…The research conducted at Mpanau involved examining 3 points within the Gumbasa area using Standard Penetration Test (SPT) data. The findings revealed that the water surface is shallow with loose sand, indicating a significant potential for liquefaction across all these points[7].Liquefaction mitigation has been discussed by several studies on the Gumbasa Canal, one of which is the use of impermeable layers[8]. Meanwhile, the influence of aquifers on liquefaction is hypothesized based on oral sources immediately after the earthquake[9].…”

Evaluation of release wells for liquefaction mitigation using numerical simulation

“…As a result of the 2018 earthquake and liquefaction disaster, the Indonesian government rehabilitated and reconstructed the Gumbasa irrigation canal designed with a concrete lining. Pratama et al [7] stated that applying impermeable lining geogrid was the best option to mitigate liquefaction on the Gumbasa Irrigation Canal when considering easy and low-cost alternatives. Apart from this mitigation, the government also plans to build release wells along the Gumbasa irrigation canal to prevent reliquefaction.…”

Study of Liquefaction Severity-induced Lateral Displacement and Settlement based on SPT Data in Toll Road Project (Case Study: Mungkid and Candimulyo Districts, Central Java, Indonesia)

“…Most liquefaction-caused lateral spreading happens on slopes with angles between 0.3 to 3, where the ground formed of loose sand and the water level is close to the surface [4]. The 2018 Palu Earthquake, which caused damage along canals, buildings, and the area of Gumbasa irrigation, was one of the lateral spreading and flow slide events caused by liquefaction that have occurred in Indonesia [5].…”