大直径泥水盾构穿越复杂环境地表垂直变形研究

Study on Ground Vertical Deformation of Large-Diameter Slurry Shield Tunneling in Complicated Environment

为研究大直径泥水盾构穿越复杂环境地表垂直变形规律,考虑盾构推力、盾体间隙及其填充、壁后间隙及其填充3个影响因素,提出了施工全过程地表垂直变形理论公式.结合武汉地铁盾构越江隧道工程,对大直径泥水盾构下穿棚户区施工全过程进行了三维数值模拟.公式计算结果与数值计算结果、监测值较为接近,吻合度高于Attewell修正的Peck公式.结果表明:(1)在分析大直径泥水盾构地表垂直变形时,需要充分考虑盾体间隙惰性填充材料的填充作用,可忽略盾壳与地层摩擦力的影响;(2)地表沉降沿隧道轴线变化曲线呈倒"S"形,开挖面后方26m(约两倍洞径)范围内土体变形速率极快,需及时加固;(3)同步注浆压力由0.3MPa提升至0.5MPa,可减小43.8%的最大沉降量,注浆压力适当提升对沉降控制作用十分明显.

To study the ground vertical deformation law of large-diameter slurry shield tunneling in complicated environment,three factors including shield thrust,steering gap and its filling,annular gap and its filling were considered.And a theoretical formula of ground vertical deformation in the whole process of construction was proposed.Combined with Wuhan Metro Shield Cross-River Tunnel Project,three-dimensional numerical simulation of the whole construction process of large-diameter slurry shield passing through shantytowns was also carried out.The formula calculation results were close to the numerical calculation results and the monitoring data,and the goodness of fit was higher than the Attewell modified Peck formula.The results show that:(1)When analyzing the ground vertical deformation of large-diameter slurry shield,the filling effect of inert filler material in steering gap should be fully considered,and the influence of friction between shield and stratum can be neglected.(2)The ground settlement curve along the tunnel axis is reverse S shape,and the soil deformation rate is very fast within26 m(about twice the diameter of the tunnel)behind the excavation face,which needs to be reinforced in time.(3)The maximum ground settlement can be reduced by 43.8%when the synchronous grouting pressure is increased from 0.3 MPa to 0.5 MPa.An appropriate increase of grouting pressure has a quite obvious effect on settlement control.