盾构与浅埋暗挖隧道小净距并行施工工法优选

针对新建暗挖隧道对已建盾构隧道的影响,以济南地铁R3线盾构与浅埋暗挖隧道小净距并行段为依托,对暗挖隧道不同施工工法进行模拟优选,分析在帷幕注浆加固条件下新建暗挖隧道对已建盾构隧道管片变形及应力的影响,并结合现场实测数据对比验证优选施工方法的可靠性.研究结果表明:暗挖隧道施工工法对于地表沉降和隧道管片的变形影响显著,其中交叉中隔墙(cross diaphragm,CRD)法和双侧壁导坑法在控制地表沉降、管片变形及应力方面差异较小,且两者均优于核心土法和中隔墙(center diaphragm,CD)法.综合考虑施工速度、影响范围以及地表与既有盾构隧道变形控制等因素,确定暗挖隧道采用CRD法施工.现场监测表明采用优选的施工工法可以保证地表变形和盾构管片变形控制在允许范围之内.

Study on the Optimization of shield tunneling and shallow buried tunnel with small clear distance in parallel construction

In view of the influence of the newly built underground tunnel on the existing shield tunnel, taking the parallel section of shield and shallow buried tunnel with small clear distance of Jinan Rail Transit Metro Line 3, the influence of the new construction tunnel on the segment deformation and stress of the existing shield tunnel under the condition of curtain grouting reinforcement is analyzed by means of numerical simulation. On this basis, different construction methods are simulated and optimized, and the reliability of the optimized construction method is verified by combining with the field measured data. The results show that the underground tunnel construction method has significant influence on the surface settlement and the deformation of tunnel segments, among which the CRD method and the double-wall guide pit method have little difference in the control of surface settlement. Both of them are better than the core soil method and the CD method. Considering the construction speed, influence scope of tunnel excavation, as well as the deformation of existing shield and the ground, the CRD method is adopted in the construction of underground tunnel. Field monitoring shows that the deformation of the ground and the shield segment can be controlled within the allowable range by using the optimized construction method.