地铁盾构近距离后行洞施工对先行洞影响的力学效应

摘要

To reveal the impacts between double holes of Suzhou Metro Line 4 adjacent tunnel shield construction, the change laws of deformation and additional stress of the first hole were obtained by using the combination of numerical calculation and field monitoring method under the construction of the second hole. The results show that adjacent construction of the second hole can cause additional secondary stress to the first hole segment in three dimensions. Among them the radial additional stress is mainly in a state of compression, the circumferential additional stress is mainly in tension state, the axial additional stresses change from compressed state to a state of tension and three kinds of stresses gradually increase and stabilize with shield tunneling of the second hole. The maximum radial additional stress caused by the construction of the second hole is about 0.028 MPa, the maximum circumferential additional stress is about 0.270 MPa, and the maximum axial additional stress is about 0.700 MPa. The deformation of segment and ground soil is affected by the soil pressure and grouting pressure significantly. The overall deformation of segment of the first hole is larger during the shield continuous construction process and the maximum deformation is about 6 mm. The ground surface changes from uplift to settlement gradually and the maximum uplift is about 1.45 mm. The surface subsidence value is bigger with the shield tunneling away and the maximum value is about 14 mm. Combined with relevant experience in construction, the impact of construction of the second hole on the first hole is acceptable, which can guarantee the stability of the structure stability and the tunnel construction.%为揭示苏州地铁4号线区间隧道盾构近距离施工双洞之间的影响,采用数值计算和现场监测相结合的手段,获得后行洞施工条件下引起的先行洞附加应力及变形变化规律.研究结果表明:后行洞近距离施工会引起先行洞管片的二次附加应力,且在三维方向均有作用;其中径向附加应力主要呈受压状态,环向附加应力主要呈受拉状态,轴向附加应力由受压状态转化为受拉状态,且附加应力随着后行洞盾构的掘进逐渐增大并趋于稳定状态;由后行洞施工引起的径向附加应力最大约为0.028 MPa,环向附加应力最大约为0.270 MPa,轴向附加应力最大为0.700 MPa;管片及地层变形受土仓压力及注浆压力的影响明显,盾构连续施工过程中先行洞管片整体变形较大,最大变形约为6 mm;地层由隆起逐渐转为沉降,最大隆起量约为1.45 mm,随着盾构的远离,地表沉降逐渐增大,最大达14 mm左右;结合相关施工经验,后行洞施工对先行洞的影响处于可接受范围内,能保障隧道施工和结构受力稳定.