Study on the Factors Affecting the Design of Deep Backfill Foundation Pit and the Factors Affecting Soil Construction Disturbance

Water is an indirect construction disturbance factor, which has important influence on the stability evaluation and analysis of foundation pit slope engineering. The study is mainly aimed at the deep backfill, the mechanical parameters are not uniform, and the effect of water on its mechanical parameters is great. The mechanical parameters of the backfill under different moisture content were measured by static triaxial shear test. The results show that the cohesion, internal friction angle and shear strength of the backfill are attenuated with the raise of the water content, the cohesion and internal friction angle of the attenuation law showed a linear re-gentle trend, and the shear strength of the decay trend gradually slowed down. The simulation results show that the mechanical parameters of backfill are reduced with the increasing number of saturation-dehydration cycles. The first degree of decay is the most significant, and finally tends to a certain value. The connection between the deterioration coefficient and the cycles follows the negative exponential function, and the mathematical expression of water deterioration was obtained finally. The study analyzes the damage mechanism of water in the construction disturbance, which has some theoretical support for the stability evaluation and disaster mitigation of the foundation pit.