高地应力富水软岩铁路隧道变形机理及施工控制措施

云南玉磨铁路曼勒一号隧道地处喀斯特地貌区，现场施工中遇围岩地应力高、变形量大、变形持续时间较长等问题，导致初支变形严重，影响施工进度，其中高地应力是导致围岩大变形的主要原因。通过建立力学模型分析与施工现场试验，提出开挖迂回导坑释放高地应力的控制措施，降低隧道围岩大变形风险。研究结果显示：通过数值模拟分析增设迂回导坑后，隧道正洞围岩变形量有效降低，拱顶沉降及拱腰收敛分别降低38.46%和58.34%,围岩塑性区最大塑性应变减小25.40%,围岩及初支结构应力减少了20%～24%。现场施工中，迂回导坑段隧道比仅开挖隧道正洞的围岩变形量减少了61.92%。迂回导坑的开挖能够有效控制变形量及变形速率，现场试验效果良好，施工进度得以加快。

Deformation Mechanism and Control Measures for Railway Tunnels Under High Ground Stress and Water-rich Soft Rock

The Manle No. 1 Tunnel of Yunnan Yumo Railway, a key project of The One Belt One Road, is located in a karst geomorphic area. During the on-site construction, problems such as high ground stress, large deformation, and long deformation duration of the surrounding rock were encountered, which caused serious deformation of the primary support and affected the construction progress. Among which, high ground stress is the main cause of large deformation of surrounding rock. In this paper, through the establishment of mechanical model analysis and construction site test, the control measures of excavating by-pass tunnelling to release high ground stress are proposed to reduce the risk of large deformation of surrounding rock of the tunnel. The research results show that the deformation of the surrounding rock of the tunnel is effectively reduced after the addition of the by-pass tunnelling through the numerical simulation analysis, the settlement of the vault and the convergence of the arch waist are reduced by 38.4% and 58.34%, respectively, the maximum plastic strain of the surrounding rock plastic zone is reduced by 25.40%, and the stress of the primary support structure has been reduced by 20-24%. In the field construction, excavation of the circuitous tunnel can reduce the deformation of the surrounding rock by 61.92%. The excavation of the by-pass tunnelling effectively controls the amount of deformation and the rate of deformation, and the field test results are good, and the construction progress can be accelerated.