Abstract In order to study the pre-grouting reinforcement effect of the pipe roof support for the shallow-buried mined tunnel in broken soft rocks, taking a certain tunnel project as the background, the MIDAS/GTS finite element software is adopted to establish three excavation models: pipe roof support with pre-grouting, single pipe-roof support and no pre-support, and then numerical simulation analysis is carried out accordingly. The results show that taking the pipe-roof pre-grouting measures, a reinforcement zone could be formed above the tunnel vault, which can bear most loads of the surrounding rocks in the area to be excavated, improve the arching ability of the ground, effectively control the surface subsidence, vault subsidence and stress concentration, and reduce surface subsidence by 52.7%, vault subsidence by 58.9%, arch foot convergence by 61.4%, invert heave by 63.8% and vertical stress by 79.2%. The pipe-roof support can significantly bear the pressure of overlying rocks, effectively decrease the bending moment of the lining, prevent the shotcrete from cracking failure and reduce the tensile force of the anchor bolt during the soil layer deformation; moreover, compared with the pipe-roof pre-grouting support, the single pipe-roof support has the same significant effect on controlling the convergence of side walls and invert heaving of the tunnel.For a shallow-buried tunnel underneath the existing important pipelines in weak and broken rocks, the pipe-roof pre-grouting support method could be adopted to ensure safe and smooth progress of the project, providing a certain reference for similar projects.
Abstract：
In order to study the pre-grouting reinforcement effect of the pipe roof support for the shallow-buried mined tunnel in broken soft rocks, taking a certain tunnel project as the background, the MIDAS/GTS finite element software is adopted to establish three excavation models: pipe roof support with pre-grouting, single pipe-roof support and no pre-support, and then numerical simulation analysis is carried out accordingly. The results show that taking the pipe-roof pre-grouting measures, a reinforcement zone could be formed above the tunnel vault, which can bear most loads of the surrounding rocks in the area to be excavated, improve the arching ability of the ground, effectively control the surface subsidence, vault subsidence and stress concentration, and reduce surface subsidence by 52.7%, vault subsidence by 58.9%, arch foot convergence by 61.4%, invert heave by 63.8% and vertical stress by 79.2%. The pipe-roof support can significantly bear the pressure of overlying rocks, effectively decrease the bending moment of the lining, prevent the shotcrete from cracking failure and reduce the tensile force of the anchor bolt during the soil layer deformation; moreover, compared with the pipe-roof pre-grouting support, the single pipe-roof support has the same significant effect on controlling the convergence of side walls and invert heaving of the tunnel.For a shallow-buried tunnel underneath the existing important pipelines in weak and broken rocks, the pipe-roof pre-grouting support method could be adopted to ensure safe and smooth progress of the project, providing a certain reference for similar projects.
YUE Hongwu1 MIAO Miao2
.Analysis on Pre-grouting Reinforcement Effect of Pipe Roofs for the Shallowburied Mined Tunnel in Soft Rocks[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(2): 111-117
2021, Vol. 58 