成都地铁9号线盾构下穿高铁隧道变形控制技术研究

Deformation Control Technology of a Shield Tunnel of Chengdu Metro Line 9 Crossing Underneath a High-Speed Railway Tunnel

为确定下穿施工对高铁隧道的影响,解决盾构下穿高铁隧道施工面临的技术难题,依托成都轨道交通9号线一期三元站—太平寺站区间盾构隧道在复杂条件下21°平面小夹角、长距离、超近距斜下穿成贵高铁隧道工程,采用Abaqus、FLAC3D软件建立三维数值模型、有限差分模型,进行盾构下穿高铁隧道施工全过程模拟分析及有限元强度折减过程的模拟分析;结合工程经验,进行以“应力补偿、主动托换地层”为核心的盾构下穿高铁隧道变形控制技术研究。研究表明:1)盾构隧道中心断面两侧高铁隧道位移变形呈对称分布;2)下穿施工对高铁轨道结构竖向位移影响较大、水平位移影响较小,轨道结构竖向位移与隧道整体沉降变形规律一致;3)采取主动防护施工控制技术及时将应力补偿率控制在70%~140%,可有效控制高铁变形;4)泥岩复合地层条件下,高铁隧道滞后沉降期长达4个月,滞后沉降量占比高达30%~40%。高铁实际变形情况与模拟分析成果基本一致,可验证本文所述变形控制理论与关键控制技术的适用性。

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 highspeed 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.