Forensic investigation of Gumbasa irrigation main canal damage due to large-scale flow liquefaction in Sibalaya caused by the 2018 Sulawesi Earthquake

Abstract

This study conducted an extensive soil investigation in the Sibalaya liquefaction area to identify the Gumbasa main canal's damage triggered by flow liquefaction. Several field tests and trenches with approximately 4 m were excavated to observe liquefied soil layers directly near the canal. A borehole, standard penetration test, and multichannel analysis surface waves (MASW) were performed beside the trench to obtain each layer's penetration resistance. This research aims to understand the landslide's whole aspect. The ground movements were analyzed by using satellite photos before and after the earthquake. The displacement of the main canal, the typical damage inventory, and the proposed reconstruction of the main canal are the focus of this study. As a result of the forensic investigation, the liquefied layers and debris flow contributing to the massive landslide were identified to impact the primary canal. The typical damage of the canal was due to surface rupture that occurred both horizontally and vertically. A solution for reconstructing the main canal is to use a flexible pipe canal structure. That will be resilient to future earthquake and ground movements, stabilize the ground downslope of the existing canal to limit the risk of future lateral movement in future earth tremors.