Reducing Lateral Swelling Pressure on Sheet Pile Walls Using EPS Geofoam and Sand Layers
摘要
Expansive soils generate substantial lateral swelling pressure on sheet pile retaining walls upon water absorption, potentially leading to structural distress. This study investigates and compares the effectiveness of EPS geofoam and sand layers in reducing lateral swelling pressure and wall displacement. A series of large-scale physical model tests were conducted using a 1:10 scale sheet pile wall (400 mm × 800 mm) under plane strain conditions with a semi-rigid toe boundary. EPS geofoam (12 kg/m3) and sand (18 kN/m3) were placed behind the wall at varying thicknesses: 2, 3, 5, and 7 cm for EPS, and 3, 5, and 7 cm for sand. Lateral pressure and wall displacement were monitored continuously for 57 days. EPS geofoam significantly outperformed sand layers. At 7 cm thickness, EPS reduced lateral pressure by 78.3% (from 27.5 to 5.97 kPa) compared to only 25.9% for sand (to 20.38 kPa). Wall displacement was reduced by 75.9% with EPS versus 37.3% with sand. Even the thinnest EPS layer (2 cm, 16.4%) outperformed all sand layers except the thickest (7 cm, 25.9%). The relationship between EPS thickness and pressure reduction is non-linear, with diminishing returns beyond 5 cm (0.5 m prototype), identified as the optimal thickness. This study concludes that EPS geofoam is a highly effective compressible inclusion for mitigating lateral swelling pressures on sheet pile walls. Sand layers are not recommended as primary pressure-reducing buffers due to their limited effectiveness and susceptibility to soil migration through intergranular voids. A thickness of 5 cm (0.5 m prototype) is recommended for practice.