铁路隧道十字交叉隔壁后拆式工法施工力学特性及其应用研究

厦(门)深(圳)铁路梁山隧道穿越L7富水软弱带使施工严重受阻。为确保隧道顺利通过L7富水软弱带,通过多种经济、技术比选,最终确定通过超前预加固措施改良地层条件后,采用十字交叉隔壁后拆式工法施工。阐述十字交叉隔壁后拆式工法的特点及施工工序,同传统CRD工法相比,该工法的最大特点是:"后拆式"的十字交叉临时支撑体系,确保在临时支撑体系拆除时,初期支护和二次衬砌已经同时承载,避免传统工法中因拆撑时应力释放导致的初期支护结构失稳风险,确保施工过程中的安全可靠性。然后通过数值计算和力学分析方法,对十字交叉隔壁后拆式工法在施工过程中的支护力学转换体系进行详细分析,得出以下结论:初期支护与临时支撑组成的支护体系,在开挖的每一步中,都是承载的主体,尽可能早地闭合成环;二次衬砌的闭合时机就是二次衬砌的支护时间,以初期支护极限位移的60%作为施工二次衬砌的位移指导值较为合理。

Research on Mechanical Properties and Application of Post-dismantled Decussated Diaphragm Construction Method

During the construction of Liangshan tunnel on Xiamen to Shenzhen railway crossing L7 rich water weak stripe area,the working processes are obstructed heavily. In order to assure tunnelling safely through the area,comparisons are made economically and technically before the adoption of the postdismantled decussated diaphragm method until the improvement of the stratum condition by advance strengthening measures. The characteristics and construction procedures of post-dismantled decussated diaphragm method are explained in this paper. Compared with the traditional CRD method,its greatestcharacteristic is "post-dismantled " decussated temporary support system. When temporary support is dismantled,the surrounding rock load is supported with primary support and secondlining at the same time to avoid instability resulted in the release of dismantling supporting stress of the primary support structure in traditional method,and ensure the safety and reliability in the process of construction. The supporting mechanics conversion system of post-dismantled decussated diaphragm method in construction process is studied with numerical calculation and mechanics analysis. Conclusions show that the main bearing structure is the support system comprised of primary support and temporary support and the support system should be shaped in circular section as soon as possible; the time for closing the second lining is the time for supporting the second lining; and 60% of the primary support limit displacement is taken reasonably to guide the second lining displacement.