Behavior of Single Pile and Pile Groups Subjected to Abrupt Collapse of Retaining Wall-Paper

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This study examines the settlement and lateral displacement of single piles and pile groups subjected to soil movement caused by the sudden collapse of a nearby retaining wall. Small-scale model tests were conducted in sand under 1-g conditions. Aluminum tube piles, with two embedment depths, were installed in different configurations, loaded to a safe level, and monitored as sections of a wooden retaining wall were released to simulate collapse.<br /><br />The results identify the collapsed wall’s height and pile embedment as the main factors governing pile response. Settlement generally increased as collapse height increased, with this effect more pronounced than the corresponding increase in lateral displacement. Shallow piles (embedment ratio 10) were more severely affected than deeper piles (ratio 20); increasing embedment reduced settlement by approximately 20–50%. For deeper piles, settlement tended to decrease as pile spacing and group size increased, while shallow piles showed the opposite trend.<br /><br />Settlement also decreased nonlinearly as the distance between the piles and retaining wall increased, consistent with reduced soil movement and greater confinement farther from the wall. The wall-distance effect was stronger for shallow piles and became less influential as the number of piles in a group increased.<br /><br />Overall, the tests show that pile foundations near a failing retaining wall can experience significant settlement, and that deeper embedment and greater separation from the wall generally reduce the impact. The findings highlight the importance of accounting for wall-collapse height, pile depth, group configuration, and proximity when assessing the safety of nearby foundations.

Keywords

pile settlement

lateral displacement

retaining wall collapse

soil movement

pile group

embedment depth

model tests

sand

foundation safety

wall proximity