Parametric study of structural parameters affecting seismic stability in slopes reinforced by pile-anchor structures

Abstract

Parametric study was performed on the seismic stability of pile-anchor slope reinforcement structures for earth retaining wall with different structural parameters. Dynamic finite element analysis and the Newmark permanent displacement method were combined to derive the dynamic time-history response of the pile-anchor structure and evaluate slope seismic stability. The effects of pile embedment, pile thickness, anchor position on the pile, anchor free length, anchor direction and anchor prestress were investigated by batch calculation under different structural conditions, and optimized design suggestions are proposed based on the numerical study. The quantitative analysis indicates that Newmark permanent displacement can effectively evaluate slope stability under seismic loading and provide an accessible approach to improve the performance-based design of pile-anchor structures. For the generalized vertical soil slope prevalent in actual slope engineering, considering the maximum factor of safety and minimum permanent displacement, it was found that the most optimized embedded depth occupies approximately 30% of the whole pile length in the soil slope, and the pile thickness is set as 1.5–2 m for superior shear and bending strength. In addition, there is a critical anchor position 3 m beneath the pile top, a threshold free length of the anchor cable of 9.5 m, as well as an optimal direction within the range of 15°–20°. Furthermore, the pile-anchor structure shows better sliding resistance with rational anchor prestress accounting for 20% of the sliding force. The slope seismic stability evaluation based on dynamic finite element analysis with different pile-anchor structural parameter conditions performed in this paper may lay a foundation for the design optimization of pile-anchor reinforcement structures for better dynamic performance.