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Study on Main Controlling Factors of Surrounding Rock Stability and Support Optimization of Deep-buried Tunnels under the Coupling Action of Anchor Bolts and Rocks
(College of Architecture and Civil Engineering, Xi'an University of Science and Technology, Xi'an 710054)
Abstract Due to significant rheological characteristics of the surrounding rocks of deep-buried tunnels, the rock deformation range and the displacement of the tunnel wall usually become stable after installing the primary support for some time. Therefore, researching the deformation range of tunnel surrounding rocks and the displacement of tunnel walls after supporting with the anchors will provide important theoretical basis for optimization of support parameters and reserved excavation volumes. In the paper, a mechanical model of interaction between pre-stressed anchor bolt and surrounding rock is established to analyze the position of neutral point and the maximum axial force, where the relative displacement between the bolt rod and surrounding rock is zero. The calculation formulae of the tunnel rock deformation range and the tunnel wall displacement under the coupling action of excavation disturbance, bolt pre-stress and pore-water pressure are deduced based on the neutral point theory of the bolt. The results show that the deformation range of tunnel surrounding rocks as well as the displacement of tunnel walls gradually increase with increase of the excavation disturbance and pore-water pressure while reduce with increase of the bolt pre-stress. Finally, the deformation range of the tunnel surrounding rocks and the displacement of tunnel walls in the extremely unstable tunnel section are calculated according to the proposed theoretical formulae to optimize the original excavation and support schemes, by taking a water diversion tunnel in the Qinling Mountains as engineering background.
Abstract：
Due to significant rheological characteristics of the surrounding rocks of deep-buried tunnels, the rock deformation range and the displacement of the tunnel wall usually become stable after installing the primary support for some time. Therefore, researching the deformation range of tunnel surrounding rocks and the displacement of tunnel walls after supporting with the anchors will provide important theoretical basis for optimization of support parameters and reserved excavation volumes. In the paper, a mechanical model of interaction between pre-stressed anchor bolt and surrounding rock is established to analyze the position of neutral point and the maximum axial force, where the relative displacement between the bolt rod and surrounding rock is zero. The calculation formulae of the tunnel rock deformation range and the tunnel wall displacement under the coupling action of excavation disturbance, bolt pre-stress and pore-water pressure are deduced based on the neutral point theory of the bolt. The results show that the deformation range of tunnel surrounding rocks as well as the displacement of tunnel walls gradually increase with increase of the excavation disturbance and pore-water pressure while reduce with increase of the bolt pre-stress. Finally, the deformation range of the tunnel surrounding rocks and the displacement of tunnel walls in the extremely unstable tunnel section are calculated according to the proposed theoretical formulae to optimize the original excavation and support schemes, by taking a water diversion tunnel in the Qinling Mountains as engineering background.
YU Yuanxiang YAO Yao WANG Jingbin WANG Fuyu KE Da
.Study on Main Controlling Factors of Surrounding Rock Stability and Support Optimization of Deep-buried Tunnels under the Coupling Action of Anchor Bolts and Rocks[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(1): 19-26
2021, Vol. 58 