考虑应变软化的软岩浅埋隧道施工工法对比研究

Comparative study on construction schemes of shallow tunnel in soft rock considering strain-softening behavior

为探求适合软岩浅埋隧道的施工工法,以某软岩浅埋隧道为依托,采用FLAC3D软件建立数值分析模型。首先根据位移释放率求得不同施工工法下的应力释放率;然后基于应力释放控制开挖的原理,对不同施工工法下隧道洞周变形及初期支护受力等进行分析;最后通过实测数据对数值模型的可靠性进行验证。模拟结果表明:CRD法对围岩受力变形的控制效果最佳,三台阶核心土法次之;三台阶核心土法下,开挖面前方围岩稳定性最好且初期支护受力最为合理。因此,推荐三台阶核心土法进行软岩浅埋隧道的开挖。

In order to seek an optimal tunneling scheme which is suitable shallow tunnel in soft rock,a se-ries of numerical tunnel model were conducted with the FLAC3 Dsoftware based on a shallow tunnel in softrock. Firstly,stress release rates of different schemes were obtained according to the displacement releaserates. Then,on the basis of the stress release controlling excavation theory,detailed analysis of the dis-placement around the tunnel and force of primary support with different tunneling schemes were performed.Finally,the reliability of numerical model was verified by comparing the field monitoring data with the nu-merical results. Numerical results indicate that the effect of the CRD method is the best in controlling thedeformation and stress of surrounding rock,and the three benches reservation core soil method follows. How-ever,the three benches reservation core soil method would give rise to a best stability of the rock in frontof the tunnel face and a most reasonable stress on the primary support. Therefore,the three benches reser-vation core soil method is recommended for the excavation of shallow tunnel in soft rock.