为解决高地应力软岩隧道建设过程中初期支护变形、仰拱隆起、二次衬砌压溃等问题，依托云临高速大亮山隧道展开大变形处治关键技术研究。该隧道大变形段具有如下特点： 1）初期支护变形累计变形量大、变形速率高、持续时间长； 2）仰拱隆起病害段落长、隆起高差大、受水影响大； 3）二次衬砌开裂破坏形态为压溃式破坏、破坏位置位于拱肩和拱顶、破坏时机为突发性破坏、破坏时间为滞后二次衬砌浇筑数月等。通过对大亮山隧道软岩大变形段的地质条件、破坏特点、变形特征及补勘结论等方面综合分析，采用理论分析、工程类比、数值模拟和现场实测等手段，提出仰拱曲率优化-初期支护双层钢架-二次衬砌加强衬砌-洞周限位锚杆等措施的大变形处治设计方案后，开展试验段施工和研究。试验成果表明： 1）试验段累计施工323 m，平均月进尺约43 m； 2）试验段支护方案较原设计方案，初期支护最大周边收敛值由1.4 m减小至0.30 m，最大拱顶沉降值由0.80 m减小至0.52 m，日均变形量由 7 cm减小至1~2 cm； 3）隧道大变形得到有效控制，初期支护无开裂、掉块，仰拱及二次衬砌未出现病害； 4）结合监测数据及现场情况，经分析总结试验段的综合支护体系方案较合理，大变形处治关键技术总体较成功。

Primary support deformation, inverted arch uplift, and secondary lining collapse often occur during soft rock tunnel construction with high ground stress. Therefore, countermeasures for large deformation of the Daliangshan tunnel of the YunxianLincang expressway are discussed. The deformation is characterized by follows: (1) large cumulative deformation amount, high deformation rate, and long duration of primary support deformation; (2) long section of uplift, and large uplift difference of inverted arch greatly affected by water; (3) sudden crushing crack damage on arch shoulder and crown after several months of secondary lining. The geological conditions, failure characteristics, deformation characteristics, and supplementary survey conclusions of the soft rock large deformation section of the Daliangshan tunnel are comprehensively analyzed using theoretical analysis, engineering analogy, numerical simulation, and onsite measurement methods. A plan for large deformation treatment, including optimization of inverted arch curvature, primary support of doublelayer steel frame, secondary lining reinforcement, and limiting anchor bolts around the tunnel, is designed, and construction and research on the experimental section are conducted. The experimental results reveal the following: (1) The cumulative construction of the experimental section is 323 m with an average monthly footage of approximately 43 m. (2) Compared with the original design, the support scheme for the experimental section reduces the maximum peripheral convergence of the primary support from 1.4 to 0.30 m, the maximum arch settlement from 0.80 to 0.52 m, and the daily average deformation amount from 7 to 1－2 cm. (3) The large deformation of the tunnel has been effectively controlled, with no cracking or falling of the primary support, and no damage to the inverted arch and secondary lining. (4) Based on monitoring data and onsite conditions, the comprehensive support system scheme for the experimental section is analyzed and summarized to be reasonable, and the key technologies for large deformation treatment are generally successful.