鲜水河构造带某深埋隧道大变形分级预测及防治建议  

Prediction and Mitigation Suggestions of a Large Deformation of a Deeply Embedded Tunnel in Xianshuihe Tectonic Fault Zone

作　　者：王哲威[1] 罗良成[1] 张广泽[1] WANG Zhewei;LUO Liangcheng;ZHANG Guangze(China Railway Eryuan Engineering Group Co.Ltd.,Chengdu 610031)

机构地区：[1]中铁二院工程集团有限责任公司,成都610031

出　　处：《土工基础》2022年第6期868-872,共5页Soil Engineering and Foundation

摘　　要：川西某深埋隧道穿越举世闻名的鲜水河断裂带,根据隧道9孔地应力测试的反演结果,采用岩体强度应力比法、地质分析法、围岩特征法等三种方法进行大变形预测,提出了针对性的工程处置措施建议。研究结论:(1)隧道实测水平最大主应力为42.74 MPa,测试深度为1 036.4 m,洞身反演地应力为5~45.2 MPa,最大地应力位于埋深1 219 m位置。(2)预测大变形等级主要以轻微、中等和强烈三种结果为主,占比分别为21%、6%、7%;(3)在预测结果基础上提出了针对性支护措施:轻微大变形可采用锚喷联合支护、喷射混凝土+挂钢筋网+钢拱架联合支护、高强喷射混凝土等措施;中等大变形可采取喷层留纵缝、喷钢纤维混凝土、可缩式钢架等联合支护措施;强烈大变形可采取加固地层、喷钢纤维混凝土、注浆、喷层留纵缝、可缩式钢拱架、长锚杆等联合支护措施。以上研究成果可为复杂构造带地区深埋长大隧道围岩大变形分级预测及防治提供借鉴。A deeply embedded tunnel in the western Sichuan crosses the world-famous Xianshuihe tectonic fault zone, which has very complicated geological conditions, such as significant elevation differences in topography, extreme climatic conditions, strong plate movement, complicated and dense fault structure, weak and broken rock mass structure, complicated hydrogeology, extremely high ground stress and other adverse environments. Large deformation hazards induced by the soft and weak rock mass in the deeply embedded tunnel remain the most prominent geological engineering challenges faced in the railway construction. The accurate prediction of the large deformation has an important contribution to the tunnel construction. Based on the back analysis results from the 9-borehole in-situ stress tests, three methods were used to predict the large deformation, namely, compressive strength stress ratio method, geological analysis method and surrounding rock characteristic method. Several targeted measures for the treatment of a large deformation tunnel are proposed. The following conclusions can be obtained:(1) the measured maximum lateral principal stress of the tunnel is 42.74 MPa at a test depth of 1036.4 meters. The back calculated in-situ stress of the tunnel is between 5 and 45.2 MPa, and the maximum in-situ stress is located at the maximum embedment depth of 1219 meters.(2) The prediction method of “calculating by multiple methods and determining the large deformation grade and section after synthetical analysis” proposed in this paper effectively ensure the objectivity of the predicted results. The grade of deformation mainly results in slight, medium and strong large deformation, the proportion of each part accounts for 21%, 6% and 7%, respectively.(3) Based on the predicted results, targeted support measures are proposed: the mitigation measures for tunnels with different deformation grade are given, as follows: Measures such as bolt support, shotcrete or shotcrete + hanging reinforcement mesh, setting steel arch

关 键 词：鲜水河构造带 大变形预测 分级方法 防治措施 

分 类 号：U456[建筑科学—桥梁与隧道工程]