Supporting Earth Pressures for Foundation Excavation Considering Suction Stress of Soil

Abstract

The infiltration, evaporation and variation of the groundwater table have significant effects on the suction stress of the soils and the supporting earth pressures of the foundation excavation. The distribution of the suction stresses above the ground water table is derived under different fluxes at the ground surface, according to the soil-water characteristic parameters and the effective degree of saturation. In consideration of the cohesive stress formed from the soil suction stress and the relevant anti sliding effect, the calculation model of supporting earth pressures for foundation excavation is established by the variational limit equilibrium method under the steady flow condition. The evolution of the supporting earth pressures is studied in detail for foundation excavation under different fluxes at the ground surface. The effects of the soil-water characteristic parameters, the ground water table and the internal friction angle on the supporting earth pressures are discussed. The results show that the suction stress is reduced because of the infiltration, and thus the supporting earth pressure increases. The larger the air-entry pressures and the pore size are, the smaller the supporting earth pressures are. The higher the ground water table is, the larger the supporting earth pressures are. In order to reduce the construction risk, the effects of the suction stress and the evolution of the potential critical sliding surface should be considered during the calculation of the supporting earth pressures.