软岩圆形隧洞衬砌支护时机现场变形监测判据研究

Theoretical Estimation of the Supporting Time in Soft Rocks Tunnels under High Initial Stress

结合软岩的应变软化力学特性,将隧道围岩状态分为弹性区、塑性区和松动区,采用非静水压力的柱状孔扩张与芬纳理论,推导圆形隧洞非静水压力下塑性区、松动区最大半径的求解公式,并结合实际工程经验建立了隧洞顶拱变形与塑性区、松动区半径大小的关系式,在此基础上结合衬砌提前施作的工程实际,提出了衬砌施作时机的收敛变形监测判据。该方法已在新疆引额济乌顶山隧洞施工、设计中得到了应用并取得了较好效果。

In combining with the strain softening mechanical properties of soft rocks, the surrounding rocks status of tunnel can be classified into the elastic zone, the plastic zone and the flexible zone. The column hole expansion of non-static water pressure and Fenner theory are adopted to deduce the solution formula for the maximum radius of the plastic zone and the flexible zone of round tunnel in the case of non-static water pressure. Also, the formula of radius sizes of the plastic zone and the flexible zone with the tunnel top arch deformation is established in combining with the engineering practice, on the basis of which and in combining with the engineering actual condition of lining construction in advance, this paper suggests the convergence deformation monitoring criterion for lining construction in time. This method has been used in Dingshan tunnel construction in Xinjiang and the better results were obtained.