Abstract The phyllite rocks are interbedded and severely weathered, with weak and developed structural surfaces. Tunnel construction in similarly layered rocks will result in large deformations in the surrounding rocks, seriously endangering the safety of tunnelling. Taking the Yangjiaping tunnel on Chengdu-Lanzhou Railway as an example and based on FLAC3D, this paper establishes a macroscopic bedding distribution model to study the deformation failure laws and support measures of tunnels in layered phyllite rocks. The research results show that the normal displacements of the rocks are obliquely distributed in an "X" shape around the tunnel, and the displacement peaks are situated at the tunnel vault and the sidewalls; the tangential displacements of the rocks are distributed in a "butterfly" pattern at a cross 45°direction of the tunnel, while the displacement peaks are located in the arch shoulders and arch foots of the tunnel, with obvious asymmetry displacement distribution; the surrounding rocks near the tunnel sidewalls mainly show tensile failure between bedding surfaces, while those near the tunnel arch mainly show dislocation slip failure between bedding surfaces. Based on the above analysis results, this paper puts forward optimizaion measures for the on-site support parameters and carries out monitoring of tunnel deformation and support stress.On-site monitoring results show that after adjustment of the support parameters, it shows an obvious control effect on the deformation of the surrounding rocks, effectively improving the asymmetric stress condition of the tunnel.
Abstract：
The phyllite rocks are interbedded and severely weathered, with weak and developed structural surfaces. Tunnel construction in similarly layered rocks will result in large deformations in the surrounding rocks, seriously endangering the safety of tunnelling. Taking the Yangjiaping tunnel on Chengdu-Lanzhou Railway as an example and based on FLAC3D, this paper establishes a macroscopic bedding distribution model to study the deformation failure laws and support measures of tunnels in layered phyllite rocks. The research results show that the normal displacements of the rocks are obliquely distributed in an "X" shape around the tunnel, and the displacement peaks are situated at the tunnel vault and the sidewalls; the tangential displacements of the rocks are distributed in a "butterfly" pattern at a cross 45°direction of the tunnel, while the displacement peaks are located in the arch shoulders and arch foots of the tunnel, with obvious asymmetry displacement distribution; the surrounding rocks near the tunnel sidewalls mainly show tensile failure between bedding surfaces, while those near the tunnel arch mainly show dislocation slip failure between bedding surfaces. Based on the above analysis results, this paper puts forward optimizaion measures for the on-site support parameters and carries out monitoring of tunnel deformation and support stress.On-site monitoring results show that after adjustment of the support parameters, it shows an obvious control effect on the deformation of the surrounding rocks, effectively improving the asymmetric stress condition of the tunnel.
ZI Xiaoyu1 SHEN Yusheng1 ZHU Shuangyan1 LUO Ningning2 YANG Jiaqi1 CAO Bangjun1
.Study on the Deformation Failure Laws and Support Measures for Tunnels in Layered Phyllite[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(3): 196-204
2021, Vol. 58 