双线盾构隧道近距离下穿城市既有运营双线隧道时空变形规律分析

Analysis of Space-time Deformation Laws of Shield Twin-tunnels Crossing the Adjacent Existing Urban Subway Twin-tunnels

随着城市轨道交通的快速发展,新建地铁隧道近距离下穿既有运营地铁隧道日渐成为常态。因此,新建盾构隧道近距离下穿既有运营隧道的综合控制技术、施工安全评价及时空变形规律成为当前研究的热点问题。以广州地铁22号线下穿既有地铁3号线为例,采用现场监测、理论分析、数值模拟等方法,重点研究了新建双线盾构隧道分别下穿既有运营双线隧道过程中的时空变形规律,特别是隧道结构、轨顶面等关键位置处的竖向变形规律。首先分析了水平定向钻孔加固范围和土体参数加固影响范围,提出了加固区岩土力学参数增强系数计算方法,确定了加固地层计算参数。然后基于精细化建模,分析了22号线左线下穿3号线时既有运营隧道的时空变形规律及隧道结构内力,并与监测结果进行了对比,对比显示计算结果与监测结果吻合度较高,充分证明了该研究提出的分析方法的可靠性,对下穿既有运营隧道安全评价及施工技术选取具有重要的借鉴意义。

With the rapid development of urban rail transit,it has been becoming normal for new subway tunnels to cross the existing tunnels.Therefore,the comprehensive control technology,construction safety evaluation and spacetime deformation law of the new shield tunnel undercrossing the adjacent existing line have become the hot issues of current research.Taking Guangzhou Metro Line 22 underpassing Metro Line 3 as an example,this paper focuses on the space-time deformation law of the new double-line shield tunnel crossing the existing double-line operating tunnel by means of on-site monitoring,theoretical analysis and numerical simulation technology,especially the vertical deformation law of key positions such as tunnel structure and rail top surface.Firstly,the reinforcement range of horizontal directional drilling and the influence range of soil parameter reinforcement are analyzed.The calculation method of strength coefficient of geotechnical parameters is proposed in reinforcement area,and the calculation parameters of reinforced stratum are determined.Based on the fine modeling,the space-time deformation law of the operating tunnel and the internal force of the tunnel structure are analyzed.Compared with the monitoring results,the coincidence degree is high,which fully proves the reliability of the analysis method.It has important reference significance for the safety evaluation and construction technology selection of the existing operating tunnel.