Research on Large Deformation Grading Control Technology for High Stress Red Layered Soft Rock Tunnels
(1.National Engineering Research Center of High-speed Railway Construction Technology，Changsha 410075； 2. School of Civil Engineering，Central South University，Changsha 410075；3. China Railway Group Limited，Beijing 100039;4. College of Civil Engineering, Tongji University, Shanghai 200092)
Abstract：
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 section, as the engineering background, this study analyzes the causes of large deformation disasters based on field geological 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 detachment 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.
YANG Yi1,
2 SHI Chenghua1,
2 etc
.Research on Large Deformation Grading Control Technology for High Stress Red Layered Soft Rock Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(5): 252-262
2024, Vol. 61 