Double-Row Pile Reinforcing on a Critical Slope at National Road in Tabanan, Bali

Abstract

Due to heavy rain, a landslide occurred on the high slope at the National Road in Tabanan, Bali, and is forecasted to reoccur. Thus, the double-row piles will be analyzed as an alternative method to improve allowable bearing capacity (qa) and slope stability to mitigate this area. This study used various 2D and 3D numerical modeling techniques to analyze the slope model under two variables: the installment of parallel and nonparallel (zigzag) pile configurations and variations in a second-row pile diameter. With the smallest diameter (D = 0.3 m), the first row of piles has a diameter of 0.6 m and a pile spacing of (s) = 4D. The reinforcing piles were installed into the actual slope model. In addition, the second-row pile diameter varies from 0.3 to 0.6 m. Considering the standardized traffic load, PLAXIS and ABAQUS were implemented to numerically analyze the factor of safety (FS) and qa of the 2D and 3D finite element method (FEM). Compared with the unreinforced reinforcement of two rows of piles arranged in parallel, the FS increased significantly by 33.06% in the 2D FEM and 32.82% in the 3D FEM. Yet, the model with a zigzag configuration enhanced the FS by 33.20% in the 3D FEM. However, the numerical models showed a slight improvement in the qa in both 2D and 3D FEM. The slope model defined the highest FS and qa with pile diameter, D2 = 0.6 m (P2D1). Additionally, a rotational type of failure occurred on the slope toe.