大跨度粘土公路隧道台阶法施工技术探讨

在寒区大跨度浅埋粘土隧道施工中，因粘土含水量大、粘结力差、受施工扰动强度易衰减快，地基承载力低，施工方式选择不当易造成隧道坍塌．结合在建天恒山隧道大里程段台阶法施工的实践，对大跨度浅埋土质隧道采用台阶法施工中的开挖支护施工工艺、施工质量控制要点等进行分析和探讨，指导了天恒山隧道的施工．天恒山浅埋粘土隧道三台阶法施工的成功应用为大跨度浅埋土质隧道的施工提供了技术资料，可供同类隧道施工借鉴．

Technique Discussion of Great Span Clay Highway Tunnel Construction with Bench Method

Because of such reasons,as the water content of clays is high, and the cohesion of clays is very bad,the strength of clays decays quickly by the effect of turbulence,the bearing capacity of the foundation is low,ect,during the construction of large-span shallowburried clay tunnel,insuitable construction mode will lead easily to collapse. Combining with bench method construction of Dalicheng phase ,the construction technique of excavation with supporting, the key points of constructing quality control of large-span shallow-burried clay tunnel through severe cold area were pointed out, these guided the construction of Tianhengshan tunnel,the success example of three benches method construction of shallow-hurried clay tunnel of Tianhengshan will provide a reference for large-span shallow-hurried soil tunnel＇ s construction, and will provide a reference for similar tunnel＇ s construction.