隧道浅埋软弱围岩段双下侧导坑施工性态  

Construction behavior of Double Down-side Drifts in a Weak Tunnel with Shallow Cover

作　　者：安永林[1] 史胜利[2] 彭立敏[1] 赵丹[1] 

机构地区：[1]中南大学土木建筑学院,湖南长沙410075 [2]中铁隧道集团有限公司,河南洛阳471000

出　　处：《公路交通科技》2009年第1期114-119,共6页Journal of Highway and Transportation Research and Development

基　　金：铁道部科技研究开发计划资助项目(2005K002-D-3);湖南省研究生创新基金资助项目(3340-74236000004)

摘　　要：针对某隧道软弱围岩下穿公路段在原台阶法施工中出现地表下沉、开裂等问题,提出双下侧导坑施工方法,分析其传力机制,并应用MIDAS软件建立仿真模型,进一步研究该工法的施工性态。结果显示:(1)该工法能改善隧道的受力,施工的关键步为环形土的开挖,核心土对隧道受力是有利的;(2)隧道的薄弱位置是侧导坑的坑脚、侧导坑和隧道的搭接地方、隧道的墙角和拱脚位置;(3)在有侧导坑条形基础的条件下,局部加固其下方的地基对改善围岩变形与结构受力的效果不明显。从经济及加固效用的角度考虑,施工时加固重点应在侧导坑的条形基础本身,如基础的厚度、侧坑与隧道的搭接地方、侧坑的拐角等;若围岩不稳定,应保证在有核心土的存在下进行处理。Confronted with accidents in a shallow-buried weak tunnel through old road using the bench excavation method, such as great subsidence and cracks in the ground surface as well as those in the preliminary support, a double down-side drifts construction method was presented. The drifts were used to detect geometry conditions and reinforce the parts underneath the tunnel. Its construction procedures and load transiting mechanism were then described. Its Construction behavior was also studied by numerical simulation using software MIDAS. Results show that （1） double-side drifts can improve tunnel load, the key construction step is arch ring excavation and core soil is good to keep tunnel steady; （2） weak parts mainly locate at wall foot of drifts, wall foot and crown foot of tunnel, and the connections; （3） reinforcement of soil under the drifts has no apparent effect on improving rock deformation and support load. Advice on construction was proposed that main parts to be reinforced are drifts （its foot depth, connection parts with tunnel, and its comers） and core soil should be kept if rock is unsteady and needs reinforcing.

关 键 词：隧道工程 双下侧导坑 施工性态 软弱围岩 浅埋 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]