Abstract:

In order to further study the force characteristics and mechanism of asymmetrical deformation of tunnel and supporting structure in layered surrounding rock under high ground stress, the variation rules of tunnel deformation, steel arch stress, and bending moment and axial force of secondary lining of Lanjiayan Tunnel on MianzhuMaoxian Highway under different stratification angles and ground stress directions are studied by field monitoring method and numerical simulation method. The study results show that: (1) The most adverse force position of layered surrounding rock tunnel usually exists in normal direction of stratification plane. (2) The asymmetrical deformation mechanism of layered surrounding rock tunnel is the normal squeezing action and tangential slip action of ground stress on stratification plane; when the angle of stratification plane is small, the crown top and invert of tunnel bear large extrusion deformation; and when the angle of stratification plane is high, the smaller the angle between ground stress direction and stratification plane is, the larger the slip deformation of position of tunnel lining under principal stress action is. The optimization measures are proposed based on the deformation and force characteristics of layered surrounding rock tunnel and tunnel lining.

Key words: high ground stress, layered surrounding rock tunnel, force mechanism of tunnel asymmetrical deformation, stratification angle, ground stress direction