浅埋弃土段大断面隧道施工力学行为研究

发布时间：2018-10-31 12:04

【摘要】：以龙洞堡机场隧道为工程背景,对弃土段隧道大变形原因进行深入分析,提出相应的改进措施,使隧道顺利通过剩余弃土段。研究结果表明,隧道所处人工弃土段与经压密原生土体物理性质存在差异,小导管与袖阀管注浆无法在弃土层扩散,反而增加了覆土重度,增大了隧道上覆荷载;实践证明对剩余弃土段采取二重管双液注浆,其效果要明显优于上述两种注浆措施;掌子面预留核心土和掌子面锚杆有效控制了掌子面前方先行位移,剩余弃土段掌子面先行位移约占总位移的15%~18%,达到减少掌子面先行位移的目的;弃土段隧道开挖,上覆土体呈现出整体下沉趋势,通过拱脚注浆锁脚锚杆可以减少初期支护拱脚、边墙脚沉降和过大水平位移;通过数值计算分析表明弧形导坑法开挖时,安全系数最小值发生在隧道仰拱中部,其量值为3.36,初期支护安全系数均大于2.4,支护体系在施工阶段是安全的。
[Abstract]:Taking the Longdongbao Airport Tunnel as the engineering background, the causes of the large deformation of the tunnel in the abandoned section are analyzed in depth, and the corresponding improvement measures are put forward to make the tunnel pass through the remaining section of the abandoned soil smoothly. The results show that there is a difference between the physical properties of the artificial abandoned soil section and the compacted primary soil in the tunnel. The grouting of small pipe and sleeve valve pipe can not diffuse in the abandoned soil layer, but increase the overburden and load on the tunnel. It has been proved by practice that the effect of double pipe and double liquid grouting on the remaining abandoned soil section is obviously better than that of the above two grouting measures. The core soil reserved for palm surface and anchor rod for palm face can effectively control the leading displacement in front of the face of the palm, and the first displacement of the face of the remaining abandoned soil section accounts for about 15% of the total displacement, so as to reduce the first displacement of the face of the palm. When the tunnel is excavated in the abandoned section, the overlying soil presents an overall subsidence trend, and the initial support arch foot, the side wall foot settlement and the excessive horizontal displacement can be reduced by grouting locking bolt at the arch foot. The numerical calculation and analysis show that the minimum safety factor occurs in the middle of the tunnel inverted arch, and the initial support safety factor is more than 2.4, and the supporting system is safe in the construction stage.
【作者单位】：合肥城市轨道交通有限公司;西南交通大学交通隧道工程教育部重点实验室;中铁二十一局集团第三工程有限公司;
【基金】：铁道部科技研究开发重大项目资助(2009G020-B-1) 中铁二院工程集团有限公司科研项目(科2013-40)
【分类号】：U455;U451

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