新近回填土地层隧道方案研究与分析

为解决新近回填土地层修建隧道及山区沟谷地形厚层回填土明洞基底处理的难题,依托巫山县早阳隧道开展研究工作。首先,对回填土地层隧道暗挖方案和明洞方案进行详细介绍和综合比选; 然后,将旋挖钻孔灌注端承桩与钢筋混凝土底板组成的桩板结构用于山区沟谷地形明洞基底回填土处理; 最后,针对明洞衬砌顶部承受的厚层回填土荷载及上方交叉市政道路荷载,对明洞衬砌结构进行设计计算,并对明洞回填材料及回填工艺提出要求。结果表明: 1)新近回填土地层隧道明洞方案具有工程难度低、施工安全风险小、工程造价低、工期可控的优势。2)旋挖钻孔灌注端承桩与钢筋混凝土底板形成的桩板结构对于山区沟谷地形厚层新近回填土具有良好的适应性,安全高效,能够较好地解决明洞基底承载力不足及沉降问题。3)合适的回填材料及合理的回填工艺对厚层回填土明洞衬砌结构有重要的保护作用。

Tunneling Scheme in Recent Backfill Strata

In order to solve the problems during tunnel construction in the recent backfill strata and foundation treatment of open-cut tunnel in the trench terrain, research work is carried out on Zaoyang Tunnel in Wushan County. Firstly, schemes of mining excavation and open-cut tunnel are introduced in detail and compared comprehensively. And then the pile-plank structure composed of rotary drilling borehole cast-in-place end-bearing piles and reinforce foundation board is used in open-cut tunnel foundation treatment in the trench terrain. Finally, in view of the heavy backfill soil load on the top of open-cut tunnel lining and the municipal road load across the top, the design and calculation of open-cut tunnel lining structure are carried out, and the strict requirements of open-cut tunnel backfilling materials and backfilling technology are carried out. The results show that: (1) The scheme of open-cut tunnel in the recent backfill strata has the advantages of low engineering difficulty, low risk of construction safety, low engineering cost and controllable construction period. (2) The pile-plank structure can adapt to the complex terrain, which is safe and efficient and can better solve the problems of scant foundation bearing capacity and the settlement of open-cut tunnel. (3) It is important to select suitable backfill materials and reasonable filling method for the protection of lining structure.