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针对大王顶隧道围岩较软弱破碎、埋深较浅、施工步骤多、难度大、处理不当极易坍塌的问题,为确保该工程能在不良地质条件下顺利安全施工,选择隧道左线出口段的K43+842为典型断面,运用FLAC建立数值分析模型,分析和比较了全断面法、上下台阶法、三台阶法、双侧壁导坑法对隧道Ⅴ级软弱破碎围岩段的围岩位移、塑性区大小和分布的影响程度。结果表明,双侧壁导坑法对围岩位移的整体控制效果最好,且施工质量最好,最适合于大王顶隧道Ⅴ级浅埋围岩段的施工。
In order to ensure the project can be smoothly and safely constructed under unfavorable geological conditions, the surrounding rock of Dawangding Tunnel is relatively weak and fragmented, shallow in depth, many construction steps, difficult and can not be handled properly. In order to ensure safe construction of the project, K43 + 842 is a typical section. The FLAC is used to establish the numerical analysis model. The full-face method, the up and down step method, the three-step method and the double-side wall pilot method are used to analyze the surrounding rock displacement , Plastic zone size and distribution of the degree of influence. The results show that the double-side wall pilot method has the best overall control effect on the displacement of surrounding rock and the best construction quality, which is most suitable for the construction of grade Ⅴ shallow surrounding rock in the Dawangding Tunnel.