双线公路隧道下穿铁路隧道不同施工工法理论研究

针对新建隧道下穿既有铁路隧道施工安全性问题,基于有限元摩尔库伦原理对不同施工工法的三维隧道交叉模型进行模拟分析。对比分析CD法、CRD法和双侧壁导坑法的新建公路隧道下穿既有铁路隧道引起的公路隧道施工不同部位稳定性演变和运营铁路隧道沉降变化,以期为类似工程提供借鉴作用。研究结果表明:对于自身隧道开挖,双侧壁导坑法在控制拱顶沉降具有一定优势,但在水平收敛上CRD法效果最好,其次是双侧壁导坑法。不同工法对既有铁路隧道的沉降影响不同,采用双侧壁导坑法公路隧道施工对既有铁路隧道的沉降影响最小,且不建议在交叉隧道处采用CD法进行施工。

Theoretical Research on Different Construction Methods for Double-line Highway Tunnel Under-passing Existing Railway Tunnel

In view of the safety issues involved in the construction of the new tunnel under-passing the railway tunnel, this paper conducts simulation analysis of 3D tunnel cross model with different construction methods based on finite element Mohr Coulomb principle. Besides,this paper studies the effect of CD method,CRD method and double side drift method respectively on the settlements of different construction parts of the highway tunnel and the operating railway tunnel,caused by the newlybuilt highway tunnel under-passing the existing railway tunnel. The results show that the double side drift method has an advantage in controlling the arch crown settlement comparatively,while the CRD method is the best in controlling horizontal displacement,and the double side drift method takes the second place.As for the settlement of the existing railway tunnel,different construction methods pose different effects,while the double side drift method adopted in the highway tunnel construction has the minimum effect. In addition,CD method is not recommended for construction in the crossing tunnels.