The deformation and unstability mechanism of surrounding rock of tunnel in the soft and gently dipping layered strata
In order to explore deformation and instability mechanism of surrounding rock structure of tunnel in gently dipping layered soft rock,a large-scale similar model test was conducted,and the self-developed computer vision measurement system PhotoInfor was used to observe and analyze the spatio-temporal evolution process of the surrounding rock deformation,and instability mechanism of surrounding rock was discussed by established a mechanical model of the surrounding rock structure.The results show that the spatial distribution characteristics of surrounding rock deformation of tunnel in gently dipping layered soft rocks show initial crack formation at the vault.With the load of surrounding rock increases,cracks appear in the left and right spandrels perpendicular to the bedding plane and con-nect with the bedding plane and vault cracks,leading to the formation of shear wedges and eventually slumping,causing surrounding rock instability.The gently dipping layered rock mass exhibits bedding lateral pressure,and the deformation of surrounding rock structure is clearly left-right asymmetrical under load.In terms of time evolution characteristics,it goes through three stages:roof fracture,span-drel instability and tunnel collapse.According to the experimental observation,at roof strata and span-drels strata,the surrounding rock structure of tunnel can be simplified into the mechanical model of sim-ply supported beam under uniform load,cantilever beam and simply supported beam under heterogeneous load,respectively,which reveals the deformation and instability mechanism of surrounding rock structure of tunnel in gently dipping layered soft rock.
tunnel engineeringstratified rocksurrounding rock structuremodel testmechanical mode
万方数据
维普
