Abstract:

The deformation and instability of surrounding rock and lining structure design of soft rock tunnel with high geostress are very important. The necessity of study of rock and soil rheology and study content and method for nonlinear rheological features of large squeezing deformation of soft rock are presented; and the definition, characteristics and international determination of large squeezing deformation of tunnel surrounding rock are introduced. The nonlinear rheological theory of large squeezing deformation of tunnel surrounding rock and its corresponding special design software development and engineering applications are introduced; and the main contents and innovations are introduced emphatically. An elasticlinearviscoelasticnonlinear large deformation viscoplastic rheology model is established based on KomamuroHuang rheology model, which can well reflect the nonlinear rheological process of 2D and 3D large deformation of surrounding rock; the secondary development is carried out on special software based on ABAQUS, which is applied to #5 fault at ridge section of Wushaoling Railway Tunnel on LanzhouWuhan Railway; the largescale yielding bolt/prestressed yielding bolt is used in Muzhailing Highway Tunnel and Dianzhong Hongceng Waterdiversion Tunnel with large squeezing deformation; and the 2D and 3D viscoelasticplasticities of nonlinear deformation are numerically analyzed respectively. Some issues need to be further studied are pointed out. The irrationalities and failure lessons of rigid support for large squeezing deformation of soft rock are summarized. A new yielding supporting and anchoring technology, largescale yielding bolt/prestressed yielding bolt, is developed, and the force mechanism, structure and 10 key design and construction parameters are introduced. The 2D numerical simulation is carried out for large squeezing deformation of surrounding rock by taking nonlinear rheological analysis of large squeezing deformation of Muzhailing Highway Tunnel and application of yielding bolt for example; and the key design parameters of yielding bolt is analyzed and calculated. The largescale yielding bolt/prestressed yielding bolt has been successfully applied to several projects, and good social and economic benefits have been achieved.

Key words: soft rock tunnel, large squeezing deformation, nonlinear rheology of rock and soil, largescale yielding bolt/prestressed yielding bolt, secondary lining