Study on the Sealing Timeliness of Surrounding Rock in Soft Rock Large-span cross Tunnel
The Daqing Mountain Tunnel,a soft rock super large span small clearance cross tunnel project with V-grade surrounding rock,is a key control project of the new Chongqing Kunming high-speed rail-way.The sealing efficiency of the initial support surrounding rock of the newly built Daqing Mountain Tunnel is crucial for the stability of the tunnel surrounding rock and the safety of the existing tunnel struc-ture.So,a study was conducted on the influence of rock sealing timeliness on the deformation of surround-ing rock in newly constructed tunnels and the deformation of existing tunnel structures through methods such as three-dimensional numerical simulation experiments and on-site monitoring analysis.The research results show that:if the stress release rate of synchronous support is less than 30%,and the initial support bearing capacity is formed within 24 hours,the deformation of the rock mass between two small clear dis-tance intersecting tunnels is reduced,and reduces the uneven attenuation and deformation of the existing tunnel's confining pressure.When the sealing efficiency of the surrounding rock of the new tunnel is good,and the relative settlement(α)of the initial support arch of the new tunnel is between 0.037%to 0.059%,which is less than the relevant regulations of 0.60%,the maximum vertical deformation and maximum hori-zontal deformation of the existing tunnel meet the requirements of relevant specifications.
surrounding rock of tunnelsoft rocklarge-spanthe sealing efficiency of the initial support
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