Abstract Based on a tunnel project of Chongqing Expressway, the numerical calculation model of stratum structure method is established, and the effect of system bolts in deep buried grade Ⅳ interbedded soft rock tunnel is simulated and analyzed. Considering the influence factors of system anchor distribution range and bolt length, the bolts setting types of tunnel initial support structure are divided into six simulated calculation conditions. The characteristics of surrounding rock deformation and plastic zone, bolt axial force and initial support axial force of tunnel in different simulated calculation conditions were compared and analyzed, and the following conclusions were obtained: (1) The axial force of the system bolt is small, which has certain control effect on surrounding rock deformation, supporting structure stress and surrounding rock plastic zone development, but the support effect is not obvious; (2) The feetlock bolts set on the side wall of the tunnel has a large effect and the effect of controlling the horizontal convergence deformation of surrounding rock is obvious. Therefore, the quality of the feet-lock bolts must be guaranteed before canceling the system bolt; (3) For the tunnel project of grade Ⅳ soft rock with deep buried mudstone and sandstone interbedding, the system bolts in the tunnel of soft rock can be cancelled through the demonstration of scientific research test sections and engineering analogy checking to meet the technical safety conditions required by the codes;(4) The effect of system bolt in deep buried grade Ⅳ interbedded soft rock tunnel is not obvious, and canceling the application of system bolts can reduce the construction process, close the initial support in time, and facilitate the deformation control of tunnel structure.
Abstract：
Based on a tunnel project of Chongqing Expressway, the numerical calculation model of stratum structure method is established, and the effect of system bolts in deep buried grade Ⅳ interbedded soft rock tunnel is simulated and analyzed. Considering the influence factors of system anchor distribution range and bolt length, the bolts setting types of tunnel initial support structure are divided into six simulated calculation conditions. The characteristics of surrounding rock deformation and plastic zone, bolt axial force and initial support axial force of tunnel in different simulated calculation conditions were compared and analyzed, and the following conclusions were obtained: (1) The axial force of the system bolt is small, which has certain control effect on surrounding rock deformation, supporting structure stress and surrounding rock plastic zone development, but the support effect is not obvious; (2) The feetlock bolts set on the side wall of the tunnel has a large effect and the effect of controlling the horizontal convergence deformation of surrounding rock is obvious. Therefore, the quality of the feet-lock bolts must be guaranteed before canceling the system bolt; (3) For the tunnel project of grade Ⅳ soft rock with deep buried mudstone and sandstone interbedding, the system bolts in the tunnel of soft rock can be cancelled through the demonstration of scientific research test sections and engineering analogy checking to meet the technical safety conditions required by the codes;(4) The effect of system bolt in deep buried grade Ⅳ interbedded soft rock tunnel is not obvious, and canceling the application of system bolts can reduce the construction process, close the initial support in time, and facilitate the deformation control of tunnel structure.
WANG Wei1,
2 LI Xianmin1 SUN Xinhai1,
2
.Numerical Simulation Study on the Supporting Effect of Bolts in Interbedded Soft Rock Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(5): 99-107
2022, Vol. 59 