To explore the influence of shield underneath tunneling on high-speed railway tunnel and address the related technical challenges,a case study is conducted on the shield tunnel between the Sanyuan station and Taipingsi station of the Phase 1 of the Chengdu metro line 9 closely-obliquely crossing underneath Chengdu-Guiyang high-speed railway with a small plane included angle of 21° and long distance.Furthermore,a three-dimensional numerical model and a finite difference model are established using Abaqus and FLAC3D software to simulate the entire process of shield tunneling underneath a high-speed railway tunnel and the finite element strength reduction process.Base on engineering experience,the deformation control technology of shield tunneling underneath high-speed railway tunnel is studied,taking"stress compensation and active underpinning stratum"as the core.The research results show the following:(1)The displacement deformation of the high-speed railway tunnel on both sides of the central section of the shield tunnel distributes symmetrically.(2)The underpass construction has a great influence on the vertical displacement of the high-speed rail track structure and a small influence on the horizontal displacement.The vertical displacement of the track structure is consistent with the overall settlement deformation of the tunnel.(3)Active protection construction control technology is adopted to control the stress compensation rate at 70%-140%in time,which can effectively control the deformation of high-speed railway.(4)Under the condition of mudstone composite strata,the delayed settlement period of high-speed railway tunnel is as long as 4 months,and the proportion of delayed settlement is as high as 30%-40%.The actual deformation of the high-speed railway is basically consistent with the simulation analysis results,validating the applicability of the proposed deformation control theory and key control technology.
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