关键词: 圆形深基坑, 地下连续墙, 接头刚度, 数值模拟, 盾构破井

Abstract:

A threedimensional finite element model is established for a ventilation shaft of Metro works, so as to study the internal force and deformation characteristics of the cylindrical diaphragm wall. By using the above model, the author analyses the effects of different joint stiffness of diaphragm wall, different segment forms of diaphragm wall and different strength grades of concrete on the deformation and internal force of the retaining structure during the construction period. The result shows that: 1) the impact of joint stiffness on the diaphragm wall is not obvious, the horizontal displacement increases slightly as the joint stiffness decreases, while the internal force of the diaphragm wall varies very little; 2) the effect of different segment forms of the diaphragm wall is more obvious; 3) compared to the 15segmentshaped retaining structure, the deformation and internal force of retaining structure with 24 segments appear smaller; 4) the deformation and internal force of retaining structure vary little when the grade of the concrete below the floor of the shaft becomes higher. According to the result, the author puts forward the reasonable supporting parameters and measures. The conclusions drawn show that the stability of the foundation pit of the ventilation shaft during excavation and diaphragm wall breaking by shield machine can comply with the safety requirements. 

Key words: deep cylindrical foundation pit, diaphragm wall, joint stiffness, numerical simulation, shield tunneling through ventilation shaft