隧道穿越断层破碎带施工方案及力学效应研究

以2022年北京冬季奥林匹克运动会重大交通保障项目延(庆)-崇(礼)高速公路第06标段玉渡山隧道为工程背景,采用FLAC 3D程序研究了隧道穿越F115断层破碎带CD法施工方案,分析拱顶沉降、水平收敛与塑性区范围,依据分析结果并结合现场监测数据,给出了锚-网-喷-钢拱架联合支护方案。研究结果表明:(1)施作支护方案后,隧道穿越断层破碎带段累积拱顶沉降为16.2mm,累积水平收敛量为22.3mm,而现场监测得到的累积拱顶沉降与累积水平收敛分别为19.3mm和26.5mm,二者较为吻合,故在后续隧道穿越断层破碎带CD法施工过程中以数值计算的方式预估隧道累积拱顶沉降、累积水平收敛等相关参数;(2)若数值计算结果显示隧道最大累积拱顶沉降量、最大累积水平收敛量较大、塑性区较为发育时,则隧道存在较大塌方风险;(3)在施作支护方案后,穿越断层破碎带段隧道的累积拱顶沉降量由51.5mm减小至19.3mm,累积水平收敛量由62.7mm减小至26.5mm,有了明显降低,且应力集中得以改善,塑性区范围亦大幅减小,隧道得以顺利穿越断层破碎带。

Research on Construction Plan and Mechanical Effect of Highway Tunnel Crossing Fault Fracture Zone

Taking the Yudushan Tunnel on the 6 th section of the Yanqing-Chongli Expressway of the2022 Beijing Winter Olympics as the project background,the FLAC3 Dprogram is used to study the tunnel construction plan of tunnel crossing the F115 fault fracture zone,and the settlement of the dome,horizontal convergence and plastic zone are analyzed.Based on the analysis results combined with in-site monitoring data,the anchor-net-spray-steel arch joint support scheme is put forward.The results show that:(1)the numerical calculation results of FLAC3 Dshow that after the support scheme is applied,the cumulative arch settlement of the tunnel through the fault fracture zone is 16.2 mm,and the cumulative horizontal convergence is 22.3 mm;the cumulative horizontal convergence is 19.3 mm and 26.5 mm respectively.The two are in good agreement.Therefore,in the subsequent tunnel crossing fault fracture zone,the CD method can be used to estimate the cumulative arch settlement and cumulative horizontal convergence of the tunnel.(2)If the numerical calculation results show that the maximum cumulative arch settlement of the tunnel and the maximum cumulative level convergence amount are large,and the plastic zone is relatively developed,the tunnel has a high risk of collapse.(3)After the support scheme is applied,the cumulative vault settlement of tunnel at crossing the fault fracture zone is reduced from 51.5 mm to 19.3 mm,and the cumulative horizontal convergence is reduced from 62.7 mm to 26.5 mm,which is significantly reduced,and the stress concentration is improved,and the plastic zone range is also significantly reduced,as such,the tunnel can smoothly cross the fault fracture zone.