沿隧洞轴线不同排列方式的复合地层变形破坏数值模拟研究

Numerical Simulation on Deformation and Failure of Mixed Ground Array with Different Arrangement along the Tunnel Axis

软硬岩层以不同排列方式组成复合地层,在隧洞工程开挖扰动作用下,软岩大变形和硬岩岩爆交替出现,使得对应力集中和大变形部位相间分布的现象开展研究变得很有意义。采用Flac^(3D)有限差分数值模拟方法,对沿隧洞轴线4种不同排列方式的复合地层变形破坏开展研究。研究内容为自重作用下4种不同排列方式下围岩位移、主应力和塑性区分布。结果表明,远离软硬岩交界面,软岩变形量增大,硬岩主应力值大。不考虑软硬岩两者接触面强度情况下,软岩塑性区范围显著大于硬岩,在接触面呈一定范围内的渐变过渡,而不是界限面上发生突变,说明软硬岩之间有相互作用影响。软岩大变形和岩爆并不是发生在两者界面上,而是在软岩和硬岩内一定距离上发生。在不考虑软硬岩界面力学参数影响情况下,位移呈较均匀对称的正态分布曲线形态。

The mixed ground composed of soft and hard rock layers in different arrangements has complex deformation and failure forms and positions under the disturbance of tunnel excavation.Large deformation of soft rock and rock burst of hard rock occur frequently under such conditions,which makes it very meaningful to study the phenomenon of alternating occurrence of stress concentration and large deformation.In this paper,finite difference numerical simulation method FLAC^(3D) is used to study the deformation and failure of mixed ground with four different arrangements along the tunnel axis under the action of gravity.The research contents include the distribution of displacement,principal stress and plastic zone of surrounding rock under four different arrangements.The results show that far away from the interface of soft and hard rocks,the deformation of soft rock increases and the principal stress of hard rock increases.Without considering the strength of the interface between soft rocks and hard rocks,the plastic zone of soft rock is significantly larger than that of hard rock,and there is a gradual transition within a certain range of the interface rather than a sudden change on the boundary surface,which indicates that there is interaction between soft rocks and hard rocks.