Study on Time-Space effect and earth berm of foundation pit

Abstract

Excavation to the bottom of the pit after the expiry date, due to time-space effect, the shear strengths of soil are decrease, which produce safe hidden trouble. The mechanism of supporting structure and backfill of earth berm is analyzed in the paper. Combined with a commercial and residential complex foundation pit in Wuhan as the engineering background, according to the shear strength index of the soil after the foundation pit is retrieved from the foundation pit monitoring data after placing, the safety of the foundation pit is calculated. Calculated by finite element software, The stability coefficient of foundation pit decreases and the horizontal displacement exceeds the allowable value in the code if no action is taken after placing. After reasonable slope top width and slope ratio were adopted to backpressure backfill of the pit, the construction of residential property adjacent to commercial plot should continue until completion. The foundation pit monitoring data are normal during the time, which indicated that the bottom earth berm with back pressure can reduce the horizontal deformation and increased stability of the foundation pit, this method can provide some reference for similar foundation pit treatment.