Seepage and Soil‐Structure Interaction Effects in Braced Excavations

Abstract

Flexible walls and struts in braced excavations are designed to provide lateral support and to ensure that wall movements during the excavation are not excessive. Lateral pressures and wall movements are influenced not only by soil conditions, but also by other important factors such as drainage conditions and soil‐structure interaction. We use finite element modeling to investigate the impact of these factors on typical strutted wall system response, focusing on the magnitude and distribution of lateral pressures and the pattern of lateral wall deflections. For permeable soils, an important factor that affects the wall system response, is movement of fluids since it not only changes the magnitude and distribution of lateral pressures behind the wall but may also induce excessive ground subsidence resulting from vertical consolidation. Lateral wall deflections also may be greater for a smooth wall due to the loss of tangential interaction between the wall and the soil backfill. Finally, a case study on excavation through layers of saturated dense sands is presented to demonstrate the utility of the numerical model in situations where some provision for drainage is clearly appropriate.