复杂地质条件下软岩隧道大变形破坏机制及开挖方法研究

发布时间：2018-07-25 10:10

【摘要】：通过对汶马高速公路鹧鸪山软岩隧道多次出现的大变形现象进行分析,文章将围岩破坏分为3大类,即软岩塑流、板梁弯曲变形及结构面滑移。针对建设过程中的大变形问题,选取了50 m典型围岩区段作为试验段,开展了两台阶开挖参数优化试验及两台阶与三台阶开挖工法的比选试验。两台阶开挖参数优化试验表明,开挖进尺以及下台阶左右侧前后间距对隧道的稳定性影响最大。开挖工法比选试验中,通过对两台阶与三台阶开挖洞周位移、围岩与初期支护间压力及钢拱架受力的对比发现,两台阶开挖方法由于一次开挖断面过大,围岩来压快,导致洞周变形值及围岩与初期支护压力值相对偏大,钢拱架安全储备相对不足。因此,对于处于复杂区域环境中的软岩隧道,应结合现场实际情况适当调整围岩的预留变形量;合理地选择开挖工法与开挖进尺,且在围岩条件很差的情况下,采用三台阶法可有效控制大变形灾害的产生。
[Abstract]:Based on the analysis of the phenomenon of large deformation in the soft rock tunnel of Partridge Mountain in Wenma Expressway, the failure of surrounding rock is divided into three categories, namely, soft rock plastic flow, plate beam bending deformation and structural plane slip. In view of the problem of large deformation in the construction process, 50 m typical surrounding rock is selected as the test section, and the optimization test of excavation parameters of two steps and the comparison test of excavation method between two steps and three steps are carried out. The optimization test of the excavation parameters of two steps shows that the stability of the tunnel is most affected by the excavation scale and the distance between the left and right sides of the lower steps. In the comparison and selection test of excavation method, it is found that the excavation method of two steps is too large and the pressure of surrounding rock is quick because of the comparison of the displacement around the excavation hole with that of the three steps, the pressure between the surrounding rock and the initial support, and the stress of the steel arch frame. As a result, the values of surrounding deformation and surrounding rock and initial support pressure are relatively large, and the safety reserve of steel arch frame is relatively insufficient. Therefore, for the soft rock tunnel in the complex regional environment, the reserve deformation of surrounding rock should be adjusted according to the actual situation of the site, the excavation method and the excavation advance should be reasonably selected, and the surrounding rock condition is very poor. The three-stage method can effectively control the occurrence of large deformation disasters.
【作者单位】：西南交通大学交通隧道工程教育部重点实验室;中国交通建设股份有限公司;
【基金】：国家重点研发计划重点专项(2016YFC0802201)
【分类号】：U455.4

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