考虑拱部效应的软弱围岩隧道掌子面稳定性控制研究

Stability Control of Tunnel Face in Soft Surrounding Rock Considering the Arch Effect

为研究软弱围岩隧道掌子面稳定性及控制方法,以新意法及拱部效应理论为基础对清泉隧道掌子面大变形及支护结构失稳机理开展研究。通过现场勘察、取样和室内试验,结合GSI围岩评级系统获取隧道围岩力学参数,提出掌子面-超前核心土预支护方案,利用有限差分方法构建清泉隧道三维数值模型分析多工况下掌子面变形规律,研究无拱效应下隧道掌子面挤出变形和围岩收敛变形特征,并提出优化方案,通过与现场监测数据进行对比,验证预支护措施对清泉隧道工作面的控制效果。结果表明,隧道掌子面挤出变形呈由中心向四周逐渐递减趋势,软弱围岩纵剖面收敛变形影响范围为1.5~2倍隧道跨度;通过数值计算和现场监测对比分析,验证了工作面预支护方案的可靠性。研究成果对类似隧道工程具有一定的借鉴意义。

To study the stability and control method of the tunnel face of the weak surrounding rock tunnel,a discussion on the mechanism of large deformation of the tunnel face and destabilization of the support structure in the Qingquan tunnel is carried out based on ADECO-RS approach and arch effect theory.By combining field investigation,sampling and laboratory test with the GSI rating system to obtain tunnel surrounding rock mechanical parameters,a tunnel face-overrun core soil pre-support scheme is proposed.The three-dimensional numerical model of the Qingquan tunnel is constructed by the finite difference method,and the deformation law of the tunnel face under multiple working conditions is analyzed.The characteristics of extrusion deformation and surrounding rock convergence deformation at the tunnel face under the no-arch effect are studied,and an optimization scheme is proposed.By comparing with the field monitoring data,the effectiveness of the pre-supporting measures in controlling the working face of the Qingquan tunnel is verified.The results show that the extrusion deformation at the tunnel face is gradually decreasing from the center to the surrounding area,and the convergence deformation in the longitudinal section of the weak surrounding rock is 1.5~2 times of the tunnel span.By numerical calculation and field monitoring,the reliability of the pre-support scheme at the working face is verified.The research results have a certain significance for similar tunnel engineering.