Analysis on Foundation Pit Deformation Considering Soil Unloading Mechanical Properties

During the excavation of foundation pit, the side and the bottom soil are subjected to a certain degree of unloading disturbance, and the strength and modulus are reduced to a certain extent. Using the soil parameters determined by the conventional triaxial test to calculate the deformation of foundation pit will produce certain errors. In order to find soil parameters more suitable for foundation pit deformation calculation. The conventional triaxial test, UU-1 unloading test with axial stress decreasing and lateral stress decreasing, IU-1.5 unloading test with axial stress constant and lateral stress decreasing, LU-2 unloading test with axial stress increasing and lateral stress decreasing were carried out on the main soil of a deep foundation pit in Zhengzhou. By comparing the numerical simulation results with the field monitoring data, the soil parameters were obtained. The results show that different stress paths have great influences on the horizontal displacement and soil settlement of foundation pit. The curves obtained by numerical simulation considering axial unloading parameters are close to the curve obtained by actual monitoring, indicating that the axial unloading experimental parameters are more valuable for engineering construction design.