Analysis of soil-pile interaction considering slope effect in integral abutment jointless bridges (IAJBs) under cyclic loading

This study systematically investigated the influence of slope effects on soil-pile interaction in integral abutment jointless bridges (IAJBs) under cyclic loading through pseudo-static cyclic tests. While existing studies on the soil-structure interaction in IAJBs had predominantly centered on level-ground conditions, the asymmetric constraint effects of sloped terrains remained inadequately investigated. To address this research limitation, three reinforced concrete piles—with varying ratios (b/d = 2.0, 0.0, -2.0) of the distance (b) from pile side relative to slope crest to the pile diameter (d)—were embedded in layered clay-sand slopes and subjected to cyclic displacements. Key results indicated that decreasing the ratio (b/d) from 2.0 to -2.0 increased the maximum damage depth by 25% and expanded the crack distribution range by 50%. The lateral load and soil reaction of the pile in the slope-facing direction decreased by 29.1% and 28.9%, respectively, while backslope values remained stable. Both the equivalent viscous damping and stiffness in the slope-facing direction degraded by 12-32%. These findings clarified the asymmetric soil-pile interaction mechanisms induced by slope effects and provided critical references for optimizing pile embedment depth and seismic design of IAJBs in sloped terrains.