兰渝铁路两水隧道地质条件极为复杂，洞身围岩为千枚岩及炭质千枚岩，属极软岩，受高地应力影响，施工时发生了挤压性大变形，变形和破坏极为严重。以现场测试和理论分析为手段，结合隧道变形特征，探索和研究了适合两水隧道的软岩变形控制技术，并得出以下结论： １）软岩隧道的变形特性及稳定性（塑性区）取决于地应力、围岩的力学特性、开挖断面等，且与围岩的支护条件密切相关； ２）通过采用加大预留变形量、加大支护刚度、多重支护，优化施工方法、适时施作二次衬砌等手段有效地控制了大变形，较好地解决了两水隧道高地应力软岩施工问题。在此基础上，提出了软岩隧道大变形分级标准及其对应的支护参数。

The geological conditions of Liangshui tunnel on LanzhouChongqing railway are very complex. The surrounding rocks of the tunnel are phyllite and carbonaceous phyllite, which belong to soft rocks. Serious squeezing deformation and failure induced by high ground stress occur during the construction of the tunnel. In the paper, technologies to control the serious deformation of the soft rocks with high ground stress in Liangshui tunnel is studied on basis of the deformation properties of the tunnel and by means of site testing and theoretical analysis. Conclusions drawn are as follows: 1) The deformation properties and stability of soft rock tunnels (plasticized zone) mainly depend on the ground stress, the mechanical characteristics of surrounding rocks and the dimension of the excavation crosssection, and are closely related to the supporting conditions of the surrounding rocks; 2) The serious deformation of the tunnel has been brought under effective control by adopting such technologies as increasing the deformation allowance, increasing the support rigidity, adopting multiple support, optimizing the construction method and installing the secondary lining timely. Finally, classification standard of serious deformation of soft rock tunnels and corresponding support parameters are proposed.