盾构壁后注浆对地表沉降影响模拟研究

结合宁波轨道交通某区间隧道施工, 研究了盾构壁后注浆对地表沉降的影响, 考虑壁后注浆压力消散和浆液固结硬化过程, 采用FLAC3D有限元软件对开挖过程模拟计算, 分析了不同注浆量和不同注浆压力下的地表沉降变化规律以及浆液硬化作用对地表沉降和管片位移的影响规律, 并将地表沉降和拱顶位移的计算值和实测值进行对比分析. 结果表明: 本工程最佳注浆量4.0~5.0m3, 最佳注浆压力约0.3MPa; 硬化作用引起的地表沉降占总沉降约5%, 引起的管片位移占总位移约15%. 针对宁波土质, 合理确定注浆量和注浆压力能够有效控制地表沉降, 合理配制浆液, 实时监控注浆量、注浆压力和浆液强度, 能够有效控制管片的上浮和变形.

Numerical Simulation of Ground Settlement Considering Slurry Hardening Effect after Grouting of Wall Formation

In order to study the effect of wall back grouting on ground subsidence, the process of excavation is simulated with a three-dimensional finite element software FLAC3D, in which the Ningbo rail transit subway tunnel construction is combined, and the wall back grouting pressure dissipation and slurry concretion process is considered. The ground surface subsidence under varying grouting pressure and the slurry hardening effect on the law of ground settlement are analyzed. Comparisons between the calculated value of surface subsidence and the corresponding measured value are made. The results show that, considering the soil characteristics in Ningbo, the grouting pressure can effectively be used to control the surface settlement, and the engineering optimum grouting amount is 4.0-5.0 m3, the engineering optimum grouting pressure is about 0.3 MPa, the surface hardening induced settlement in total settlement is about 5%, and induced segment displacement in total displacement of about 15%. The good combination of slurry, real-time monitoring of grouting pressure and grout strength can effectively control the floating of segment and deformation.