Research on Large Deformation Grading Control Technology for High Stress Red Layered Soft Rock Tunnels
High-stress red layer soft rock is a common adverse geological condition in tunnel construction in South-west China,where tunnels often experience large deformation caused by extrusion when passing through such strata.Taking the Xinhua tunnel on the Yuxi-Mohan Railway,which passes through a high-stress red layer soft rock sec-tion,as the engineering background,this study analyzes the causes of large deformation disasters based on field geo-logical conditions,structural damage characteristics,and deformation monitoring data.It proposes a graded control technology for large deformation of soft rock tunnels in high-stress red layers.The effectiveness of the control scheme is verified through numerical simulation and field application.The research results indicate that the stratum of the large deformation section in the Xinhua tunnel is a typical red layer soft rock with characteristics such as high deformation rate,large deformation magnitude,and prolonged deformation duration.Issues like cracking and detach-ment of initial support,deformation and twisting of steel arch frames,encroachment of initial support,and failure of small conduits were observed.The main causes of large deformation in the Xinhua tunnel include the coupled effects of high in-situ stress,weak strata conditions,strain softening,and volume expansion effects of red bed soft rock,as well as untimely support.The large deformation was categorized into three levels:slight,moderate,and severe,according to the stress-to-strength ratio of the surrounding rock.For each deformation level,a corresponding control scheme was proposed.Numerical simulations and field applications demonstrated that the adjusted control schemes significantly reduced the deformation of the surrounding rock,with the deformation of the surrounding rock within the reserved range under all three control schemes.
High in-situ stressRed layer soft rockLarge deformationConstruction control technology
万方数据
维普
