摘要
泥石流堆积体通常由砂砾、卵石和漂石组成,夹杂淤泥质粘土,结构松散、胶结性差,隧道施工极易引起拱部超挖甚至坍塌。以国道318线林芝—拉萨段娘盖村隧道为工程背景,在三台阶七步开挖法的基础上优化提出了一种互补循环式开挖工法,并建立相应的隧道动态分部开挖三维数值模型,分别进行隧道穿越泥石流堆积体时优化前和优化后工法开挖的模拟分析。结果表明:采用优化后的工法进行隧道开挖时围岩总体变形明显降低,拱顶沉降减小了38.8%,水平收敛减小了36.5%,地表沉降最大值仅为优化前的60%左右;初期支护弯矩减小了25.7%、锚杆轴力减小了39.8%,表明优化后的开挖工法在控制隧道变形以及减小支护结构受力方面效果显著。研究结果可为隧道穿越泥石流堆积区开挖工法的选择提供参考。
The debris flow accumulation is generally composed of gravel,cobble and boulder,mixed with muddy clay.Its characteristics are of loose structure and poor cementation.Overbreak and collapse are highly likely to be caused by tunnel construction at the arch.Based on Nianggai village tunnel in Nyingchi-Lhasa section of national highway 318,a complementary circulating excavation method was proposed on the basis of Three-bench Seven-step excavation method.The three-dimensional numerical model for tunnel dynamic excavation was established,and the optimized simulation results were compared with the original one.The results show that the overall deformation of surrounding rock is significantly decreased when the optimized method is used for tunnel excavation.The vault settlement and horizontal convergence are reduced respectively 38.8%and 36.5%.The maximum value of surface settlement is approximately 60%of that compared with the original method.The bending moment of primary support is reduced by 25.7%,and the axial force of bolt is reduced by 39.8%.It is indicated that the optimized excavation method is highly effective to control tunnel deformation and reduce the stress of supporting structure.The research results are supposed to provide reference for the selection of tunnel excavation method in debris flow accumulation.
作者
昝文博
钟宇健
唐琨杰
冯志华
ZAN Wenbo;ZHONG Yujian;TANG Kunjie;FENG Zhihua(School of Civil Engineering,Shaanxi Polytechnic Institute,Xianyang 712000,China;School of Highway,Chang'an University,Xi'an 710064,China;Hebei Provincial Communications Planning and Design Institute,Shijiazhuang 050011,China)
出处
《甘肃科学学报》
2022年第2期110-114,144,共6页
Journal of Gansu Sciences
基金
陕西工业职业技术学院计划项目(2020YKYB-016)
陕西省重点研发计划项目(2020SF-428)。
关键词
泥石流堆积体
隧道工程
开挖工法
数值模拟
围岩变形
Debris flow accumulation
Tunnel engineering
Excavation method
Numerical simulation
Surrounding rock deformation
