The Slope Instability Potential in the Balaroa area based on the Finite Element Method using Shear Strength Reduction

Abstract

Balaroa area is an alternative road connecting Palu City with Sigi and Donggala Regencies which experienced landslides due to the September 2018 earthquake. The landslide formed a steep slope and was prone to landslide. This study is to determine slope stability and design of optimal and safe slope geometry against landslides. Input and data analysis based on the Finite Element Method using Shear Strength Reduction with the help of RS2 software. The analysis resulted safety factor (SF) value on the existing slope without an earthquake load at locations 1 and 2 is in a stable condition with SF>1, after being given an earthquake load of 0.35g, the SF<1, while location 2 remained safe under the earthquake load with SF> 1. The total value of displacement on existing slope without earthquake load at location 1 was 0,006-0,040m and location 2 was 0,01-0,1m, after being given an earthquake load, it decreased 0,0045-0,030m at location 1 and increased 0,006-0,15m at location 2. This illustrates the existence of an earthquake greatly affects SF and total displacement. Safe slope geometry design for location 1 is slope height must be 10,2m with angles of 46° for level 1and 32° for level 2, with SF value 1.25.