Numerical analysis of pile—slope stability and the soil arching around two adjacent piles

Seismic pile—slope stability analysis and the formation mechanism of soil arching have not been well studied. This study used a three-dimensional (3D) finite difference to determine soil and pile parameter changes in the static and seismic stability of the pile—slope caused by the interaction between stabilizing piles. Pile—slope stability analysis was performed to determine the optimal design of piles along a slope and the corresponding failure mode involving the formation of soil arching around two adjacent piles. The Factor of Safety (FS) of the slope was evaluated using the shear strength reduction method for static and seismic analyses. The results of the analysis show that suitable pile spacing (S) and a suitable pile diameter (D) in the middle of a slope result in the maximum FS for the pile—slope system and the formation of soil arching around two adjacent piles. FS of the pile—slope increased negligibly in the seismic analysis of piles located at the slope crest and toe. An optimized pile diameter and installation location afforded the maximum FS for the slope that corresponded to a specified slope failure mode for different pile locations. A pile spacing S ≤ 2.5D for piles installed in the middle of the slope is suggested for increasing the static and seismic pile—slope stability.