关键词: effective degree of saturation, suction stress, supporting earth pressure, variational limit equilibrium
method

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.

Key words: effective degree of saturation, suction stress, supporting earth pressure, variational limit equilibrium
method