大断面浅埋黄土隧道围岩变形特性分析

发布时间：2018-09-11 19:10

【摘要】：以忻州大断面黄土隧道为工程背景,针对三台阶七步开挖法施工条件下的围岩变形特性进行了现场测试分析,采用Midas/GTS三维有限元软件进行施工模拟分析,并结合隧道围岩位移弹塑性解析法进行了验证。分析结果表明:地表沉降、拱顶下沉及洞周水平收敛随上、中、下台阶的开挖变化较大,尤其是下台阶的开挖,其收敛出现突变;仰拱浇筑前,拱顶和地表沉降及洞周水平收敛占总变形比例分别为85%、80%和90%,且仰拱施作完成后变形基本稳定;各部位围岩内部位移与距开挖轮廓线距离成反比,距开挖轮廓线4.5 m处约为1.5 m处的24~50%,且拱顶和拱脚处围岩内部位移较明显,数值计算塑性破坏区分布与实测结果吻合;支护时机与强度对围岩后期变形仍存在一定的影响,拱脚是施工中的薄弱部位,应提高支护强度;拱顶下沉数值计算和弹塑性解析解与实测结果变形规律基本吻合,且较实测值分别大16%和11%。
[Abstract]:Taking Xinzhou large-section loess tunnel as the engineering background, the deformation characteristics of surrounding rock under the construction condition of three-step and seven-step excavation method are tested and analyzed on the spot, and the construction simulation analysis is carried out by using Midas/GTS three-dimensional finite element software. Combined with the elastic-plastic analytical method of surrounding rock displacement of tunnel, it is verified. The analysis results show that the ground subsidence, dome subsidence and horizontal convergence around the hole follow the upward, the excavation of the middle and lower steps, especially the excavation of the lower steps, the convergence of sudden change, before the inverted arch pouring, The proportion of total deformation of arch roof, surface subsidence and horizontal convergence around the tunnel is 85% and 90% respectively, and the deformation of inverted arch is basically stable after completion, the internal displacement of surrounding rock is inversely proportional to the distance from the contour of excavation. It is about 1.5 m from the excavation contour, and the internal displacement of the surrounding rock at the arch top and arch foot is obvious. The distribution of the plastic failure zone in the numerical calculation is in agreement with the measured results, and the timing and strength of the support still have some influence on the late deformation of the surrounding rock. The arch foot is the weak part in the construction, and the support strength should be improved, and the numerical calculation and elastic-plastic analytical solution of the arch roof subsidence are in good agreement with the measured results, which are 16% and 11% larger than the measured values, respectively.
【作者单位】：同济大学道路与交通工程教育部重点实验室;中铁二十五局集团第五工程有限公司;铁道部第三勘察设计院集团有限公司;
【分类号】：U455.4

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