Analysis of Soil-Pile Interaction Considering Slope Effect for Integral Abutment Jointless Bridges (Iajbs) Under Cyclic Loads

Abstract

This study systematically investigates slope effects on soil-pile interaction mechanisms in Integral Abutment Jointless Bridges (IAJBs) through pseudo-static cyclic tests and nonlinear finite element analysis. Three reinforced concrete piles with variable slope distance ratios (b/d = 2.0, 0.0, -2.0) embedded in layered clay-sand slopes were subjected to seismic-level cyclic displacements. Key findings demonstrate that reducing b/d from 2.0 to -2.0 induces a 25% increase in maximum damage depth (6.0d→7.5d) and 50% expansion of crack distribution range (4.4-8.3d→4.5-12.2d), while decreasing horizontal force capacity under slope-side loading by 29.1% and soil reaction at ±30 mm displacements by 28.9%, with push-direction responses remaining stable (±5% variation). The equivalent viscous damping and stiffness under pull degrade by 12-32% and 12-23%, respectively. Comparative analysis revealed sand-embedded piles exhibit 40-60% higher energy dissipation capacity and 10-30% slower stiffness degradation than clay-slope counterparts due to enhanced soil densification. Parametric FE analysis established critical thresholds: slope effects become negligible when b/d > 4 or slope angles < 20°, with maximum soil reactions shifting from 1.2d to 10d depths as slope inclination increases. These quantitative results elucidate asymmetric soil-pile interaction mechanisms under combined cyclic-seismic loading, providing critical benchmarks for optimizing pile embedment strategies and informing performance-based seismic design codes for IAJBs in mountainous terrain.

Keywords: Integral abutment jointless bridge (IAJB), Slope effect, Pseudo-static cyclic test, Finite element analysis, Soil-pile interaction