Abstract: The high-pressure jet grout formed column in soils can effectively improve the overall shear strength of soft soils. It is an important content to evaluate and analyze the reinforcement effect of the high-pressure jet grout formed columns in deep excavation projects. In this paper, throughout a deep excavation project in Nanjing, a three-dimensional finite element models were established before and after the soil improvement using high pressure jet grout method. The bending moment, lateral displacement and the shear force in the supporting structures before and after reinforcement were compared. Further, the maximum lateral displacement at the supporting structure, the maximum rebound at the excavated base and the maximum settlement of the ground surface behind the excavation with studied with different jet grout formed wall thicknesses. The results show that after the high-pressure jet grout reinforcement, the moment, lateral displacement and establishment in the support structure are effectively reduced, and the lateral displacement in the support structure decreases by about 50%; with the increase of the column wall thickness, the maximum lateral displacement of the support structure, the maximum rebound at the base of the excavation and the maximum surface settlement behind the excavation decrease exponentially, and tend to converge gradually.

Key words: high pressure jet grouting columns, deep excavation, soil improvement, mechanical parameters, numerical simulations