Reasonable Cross Section Size and Stress Peak Transfer Mechanism of Middle Pilot Tunnel in Super Deep Buried Soft Rock Tunnel
In the super-deep soft rock tunnel,high crustal stress is typically encountered,and the surrounding rock is characterized by weakness and fragmentation.Substantial deformation is inevitably induced during the construction process,causing failure of the support structure.The utilization of advanced pilot tunnel stress release technology is employed for the advance release of crustal stress,aiming to enhance the stress state of the support structure,diminish tunnel deformation,and ensure the safety of the support structure.Based on the Haba Snow Mountain Large Deformation Tunnel on the Lixiang Line,literature research,numerical simulation,and on-site monitoring were used to study the reasonable section size of the advanced middle guide tunnel in a super deep soft rock tunnel.The stress release effect under different section sizes of the middle guide tunnel was analyzed,and the reasonable section size of the middle guide tunnel was ultimately determined.The stress release effectiveness was analyzed across different cross-sectional dimensions of the middle pilot tunnel,ultimately leading to the determination of the appropriate cross-sectional dimensions for the middle pilot tunnel.The research findings demonstrate that the stress release is most effective when the cross-sectional area of the leading middle tunnel is 0.6 times that of the main tunnel.In comparison to the direct excavation of the main tunnel,the utilization of a suitably sized advanced middle pilot tunnel section results in a reduction of 28.2％,27.64％,and 26.71％in the settlement of the main tunnel arch crown,horizontal convergence values of the upper and lower steps,respectively.Additionally,the peak tangential stress in the surrounding rock shifts approximately 4 m into the deeper part of the surrounding rock,and the peak stress value is reduced by approximately 5.04％.The research outcomes can offer valuable reference and insights for similar large deformation tunnel projects.
super deep buriedlarge deformation tunnelstress release technologymiddle pilot tunnelcross section size
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维普
