地铁盾构隧道近距离下穿广深铁路影响分析及防护措施研究

Impact Analysis and Study on Protective Measures of Shield Tunnel Closely Undercrossing Guangzhou-Shenzhen Railway

地铁区间隧道近距离下穿既有运营铁路安全风险较大,对运营铁路影响较大;为降低安全风险,在分析区间隧道下穿施工对铁路影响的基础上,研究铁路的安全防护措施,以减少对运营铁路的影响。以深圳地铁5号线盾构区间隧道近距离下穿广深铁路为研究背景,通过理论分析、数值模拟计算、工程类比研究方法,分析盾构区间隧道下穿施工引起的铁路桥梁及承台沉降、差异沉降、时程曲线,桥梁桩基的位移。根据模拟计算结果,结合具体工程技术条件,研究地铁盾构隧道下穿广深铁路的安全防护措施,通过对桩基预注浆加固、主动托换桥梁桩基、桩基补强3个方案的综合比选分析,并对选用方案进行验证分析。研究结论:桩基补强方案,即在既有桥梁桩基附近增设桩基,施作承台并与既有承台连接,可以提高桥梁桩基承载力和抗变形能力,减少地铁盾构隧道下穿施工对铁路的影响,能够确保铁路的正常运营。

There exists enormous risks and big impact where shield tunnels closely undercrossing the existing railway,which greatly affects the operating railway.In order to reduce safety risks,this paper,based on the analysis of the impact of tunnel undercrossing the railway,studies the safety protection measures to reduce the impact on the operating railway.With reference to Shenzhen Metro Line 5 shield tunnel undercrossing Guangzhou-Shenzhen Railway,the settlement of railway bridge and cap,differential settlement,time history curve,bridge pile foundation displacement are analyzed through theoretical analysis,numerical simulation calculation and engineering analogy research.According to the simulation results and combined with the specific engineering and technical conditions,safety protective measures of shield tunnels undercrossing Guangzhou-Shenzhen Railway are studied.The comprehensive comparison and analysis of three schemes of pre-grouting reinforcement,active underpinning bridge pile foundation and pile foundation reinforcement are carried out,and the selected scheme is verified and analyzed.The research concludes that the pile foundation reinforcement scheme,that is adding a pile foundation near the existing bridge pile foundation,serving as a pile cap and connecting with the existing pile cap,can improve the bearing capacity and deformation resistance of the bridge pile foundation,reduce the impact of subway shield tunnel undercrossing construction on the railway,and ensure the normal operation of the railway.