矿山法隧道拱部装配式衬砌结构设计研究

为解决矿山法铁路隧道施工拱部常出现的衬砌背后脱空、二次衬砌厚度及强度不足等质量缺陷问题，提出矿山法隧道拱部采用装配式预制管片结构的新思路，并基于时速350 km双线铁路隧道，采用数值计算分析研究拱部装配式衬砌结构的系列设计参数。主要研究结论有： 1）提出拱部装配式衬砌环向不分块的整体预制形式，综合考虑理论计算结果、行车安全分析、机械设备运输及拼装能力、拱部衬砌承载能力等，确定拱部管片环向弦长8.6 m、纵向幅宽2 m、衬砌厚度50 cm的结构尺寸及配筋设计参数； 2）提出拱部预制管片之间环缝采用螺栓连接、拱部预制管片与现浇边墙采用“L”型榫接头的接头形式及其设计参数； 3）为保证拱部管片的顺利安装，“L”型榫接头应考虑一定的施工误差，同时拱部预制管片与初期支护间应预留安装空间，后期通过管片背后纵向注浆填充密实。隧道拱部装配式衬砌技术成功应用于重庆胡家沟隧道，总体实施效果较好。

Design of Prefabricated Lining Structure at Tunnel Arch Constructed with Mining Method

Tunnels constructed by mining methods always have many problems such as voids behind the lining structure and insufficient thickness and strength of secondary lining. Accordingly, a novel prefabricated segment for the tunnel arch is proposed. Based on a double track tunnel with a speed of 350 km/h, a series of design parameters of prefabricated tunnel lining at tunnel arch are studied using numerical calculation and analysis methods. Main conclusions are drawn as follows: (1) The integral prefabrication form of arch fabricated lining in the circumferential direction is proposed. Considering the theoretical calculation results, traffic safety analysis, transportation and assembly capacity of mechanical equipment, bearing capacity of arch lining, etc., the structural dimensions and reinforcement design parameters of arch segment circumferential chord length of 8.6 m, longitudinal width of 2 m, and lining thickness of 50 cm are determined. (2) The arch pre production tube slice is connected with each other by bolts, which also be connected with cast in place sidewall by L type tenon joints. Meanwhile, the dimensions design parameters of the tenon joints are proposed. (3) To ensure the smooth installation of arch segments, the construction error should be considered for the tenon joint of cast in situ sidewall, and an installation space shall be reserved between the arch segment and the primary support. After the segment is installed, the space between surrounding rock and segment shall be filled and compacted by longitudinal grouting at the back. The prefabricated lining at tunnel arch has been successfully applied to the Hujiagou tunnel in Chongqing, China, and the overall implementation effect is good.