由于软质岩具有饱水软化、蠕变的工程特性,这使得软质岩隧道围岩大变形成为国内一些类似隧道的共性问题。从麻竹高速公路黄家寨隧道进口二衬开裂问题入手,研究在复杂地质条件下隧道围岩工程力学特性,从围岩岩性、岩体结构、强度及变形特征、地下水作用等角度出发,全面分析了隧道进口二衬开裂的原因,发现围岩破碎、岩质较软、高水敏性及强蠕变性是主要原因,并据此提出了增加钢花管全断面径向注浆长度、加强隧道初期支护和二次衬砌及预留永久性排水孔的处理措施。 Due to the engineering characteristics of soft rock with water softening and creep, this makes the large deformation of soft rock tunnel wall become a common problem of some similar tunnels in China. Starting from the cracking of the second lining of entrance of Huangjiazhai Tunnel in Mazhu Expressway, the mechanical properties of surrounding rock of tunnel under complex geological conditions are studied. From the aspects of the lithology of surrounding rock, the structure of rock mass, strength and deformation, groundwater effect, The reasons for the cracking of the second lining of the tunnel are analyzed comprehensively. It is found that the surrounding rock is broken, the rock is soft, the high water sensitivity and the strong creep are the main reasons. Therefore, it is proposed to increase the radial grouting length of the full section of the steel pipe and to strengthen the tunnel Initial support and secondary lining and the provision of permanent drainage holes treatment measures.