Comparison of horizontal push-pile model tests between non-beam double-row anti-slide piles and single-row anti-slide piles

In large-scale landslide control engineering design, the selection of anti-slide pile support is a critical design consideration. To investigate the effectiveness of double-row anti-slide piles compared to single-row reinforcement for slopes, this study conducted comparative tests of unconnected double-row piles and single-row piles using a large-scale physical simulation model, and the differences in slope damage modes and pile force characteristics were analyzed in depth. The results indicate that during slope failure, single-row piles exhibit soil arching effects between the piles, while double-row piles form “eight”-shaped cracks due to flow around the piles, with the rear piles experiencing bending. Both single-row and double-row piles exhibit four stages of deformation characteristics in their pile head displacement curves: densification deformation, elastic deformation, accelerated deformation, and plastic failure. In the accelerated deformation stage, the pile head displacement of rear piles is approximately twice that of front piles for double-row piles, and for single-row piles, it is approximately 1.5 times that of the front piles. Due to the “shielding effect”, the anti-slide effect of double-row piles is approximately 15% higher than that of single-row piles. The lateral soil pressure along the pile body generally exhibits a triangular-trapezoidal distribution, with the soil pressure behind the pile greater than that in front of the pile. Regarding pile bending moments, both exhibit a distribution trend similar to a parabola, with the maximum moment occurring near the sliding surface (7 cm above it). Additionally, under the same horizontal thrust, the rear pile experiences the maximum bending moment, followed by the single-row pile, while the front pile experiences the minimum bending moment. The presence of rear piles reduces the maximum bending moment of front piles by approximately 27% compared to single-row piles, thus enhancing the anti-slide effect of the pile. These findings provide guidance for the design and treatment of landslide control engineering projects.