炭质页岩隧道台阶法施工开挖进尺优化研究

Research on Optimization of Excavation Footage of Step-construction-method of Tunnels in Carbonaceous Shale

以牡绥线兴源隧道为工程实例,结合现场对应力和变形的实际监控量测,运用有限元分析方法对不同开挖循环进尺下的隧道三台阶预留核心土施工方法进行数值模拟,分析了围岩位移和支护结构受力的响应规律.结果表明:围岩纵向位移和水平收敛主要分布在拱顶至拱腰处,且其变形量大、变化快、变形时间长;开挖循环进尺越小,掌子面和已经施作的支护对新开挖的围岩在纵向上的约束作用越明显,且支护能够尽早封闭,从而有利于减小围岩的变形.

This paper takes Xingyuan tunnel of Mu-Sui line as an engineering example, combines with the actual monitoring of stress and displacement, uses the finite element analysis method to three-steps-seven-footwork of tunnel construction method under different excavation circulation footage for purpose of numerical simulation, ana- lyzes the response law of displacement of surrounding rock. Research shows that longitudinal and level displace- ment of the surrounding rock are mainly distributed between the area of vaults and hance, and it has the feature of large deformation, quick change and long deformation time;The smaller excavation circulation footage, the more obvious the effect of longitudinal constraint function that applied to the new excavation surrounding rock. At the same time, the support can be closed as soon as possible, so that it can reduce the deformation of surrounding rock.