Abstract: In deep excavation sites, due to the engineering characteristics of the high water content and the low strength of soft soils, the excessive deformation of the deep excavation often leads to safety hazards. Therefore, the design concept of the deep excavation strength control has been transformed into a concept of the deformation control of the excavated area. To reduce the deformation of the deep excavation in soft soils, the Hubei Provincial Technical Specifications for Foundation Excavation Engineering (DB42/T159-2012) qualitatively stipulates the use of cement-soil mixing columns to improve the passive zone in a stepped pattern, but no specific theoretical basis is provided for the width and depth of the reinforcement. Based on the strength parameters of soft soils, the width of the excavated area with the added solid is determined using the limit equilibrium method, and the numerical simulation is conducted to analyze the deformation characteristics of the reinforcement area. The relative relationship between the soil layer strength parameters and the width of added solid is obtained, and the feasibility of the adopted reinforcement method is verified by comparing the actual engineering monitoring data with numerical simulation results.

Key words: Passive Reinforcement Zone, Resistance to Heave, Shear Strength Parameters, Numerical Simulation