English：

The first phase project of Jinan Rail Transit Line 4 is located in the confined water stratum ofthe spring area. The confined water in the project area has large buried depth, high water head and largewater volume, and there are great safety hazards in the construction of deep and large foundationexcavation. Based on ABAQUS finite element software, a two-dimensional numerical model of site-underground diaphragm wall-dewatering well is established. It is analyzed and pointed out that theconfined water at the bottom of the foundation excavation will lead to adverse phenomena such asfoundation excavation swell and bottom rebound. Based on the basic theory and practical engineeringexperience, the bottom sealing reinforcement technology of deep and large foundation excavation isproposed by using ultra-deep three-axis mixing pile to reinforce the base soil layer and RJP jet groutingpile to strengthen the joint. The research shows that the technology can effectively control the groundwaterpressure of the basement and reduce the internal force of the lateral support of the foundation excavation,reduce the adverse effect of the basement rebound and ensure the safe excavation of the foundationexcavation.