为有效控制高应力软岩隧道大变形灾害的发生，以木寨岭公路隧道为依托，采用资料调研、理论分析和现场试验相结合的手段，在分析围岩变形机制与成因的基础上，提出并开展复合型大变形控制技术与实践的研究。主要结论如下： 1）高应力引起的炭质板岩的塑性流动和薄层状结构的板梁弯曲变形是木寨岭隧道大变形的主要机制，相应围岩变形的主要影响因素包括应力场、围岩条件、地下水、支护理念与技术和施工技术等； 2）传统及时强支护理念与技术难以适用于严重挤压变形段，易出现支护体系的拆换； 3）施作注浆导管，优化钢拱架拱脚工艺，掺入抗裂纤维和打设泄水管等施工优化措施可取得一定的变形控制效果； 4）提出隧道主动支护的2层含义，组建复合型初期支护体系，通过现场支护体系试验，验证了其良好的大变形控制效果，并在结合施工优化措施的基础上，最终实现了2#斜井初期支护拆换率由30%到0的转变。

The mechanism and causes for the surrounding rock deformation of Muzhailing highway tunnel are analyzed using data investigation, theoretical analysis, and field test, and the composite large deformation control techniques are proposed and put into practice to effectively control the large deformation disaster of soft rock tunnel with high geostress. Following are the primary conclusions: (1) the plastic flow of carbonaceous slate and bending deformation of platebeam with thin layer structure caused by high geostress are the main causes of Muzhailing tunnel′s large deformation mechanism, and the main corresponding causes include initial stress field, surrounding rock conditions, groundwater, support concept and system, and construction technology; (2) the traditional timely and robust support are ineffective in areas with severe extrusion deformation, where the support system often needs to be withdrawn and rebuilt; (3) deformation control is achieved through construction optimization techniques such as postconstruction grouting conduit, optimizing steelframe archfoot installation technology, and using anticrack fiber and drain pipe; (4) a composite primary support system is built using the two meanings of tunnel active support theory. According to the field support system test, the composite primary support system has a good major deformation control effect. Finally, the replacement rate of the primary support of inclined shaft No. 2 is reduced from 30% to 0% owing to the construction optimization measures.