隧道软弱围岩的受力变形研究

Study on Stress and Deformation of Weak Surrounding Rock of Tunnel

软弱围岩由于岩性软弱、整体性差等特点成为了隧道开挖过程中的研究重点。该文主要研究了隧道软弱围岩的受力变形,首先选取不同类型的软岩作为研究对象,采用预留核心土的三台阶法进行施工,利用ANSYS有限元软件进行数值模拟,分析了不同等级的软岩的受力变形特点以及仰拱对于围岩稳定性的影响。研究表明:在开挖过程中,隧道上台阶、下台阶周边岩体在水平方向上有明显阶段性变形,且上台阶对拱顶围岩扰动最大,易产生较大沉降;岩体被挖出时剩余围岩转角处易出现应力集中现象从而导致局部围岩发生失稳破坏;仰拱能够有效限制围岩的变形,减少围岩内部应力,从而提高隧道的整体稳定性。

Because of weak lithology and poor integrity of the weak surrounding rock,it has become one of the key research objects in the process of tunnel excavation.This paper mainly studies the characteristics of soft rock and the research status of soft rock at home and abroad,and takes five different types of soft rock sections as the research object,it adopts the three-step method of reserving core soil for construction.ANSYS is used as finite element software to carry out numerical simulation for each excavation step.The changes of different grades of soft rock in the excavation process are analyzed.According to the research:During the excavation process,the rock mass around the upper and lower steps of the tunnel has obvious stage deformation characteristics in the horizontal direction,and the excavation of the upper stage has the greatest disturbance to the surrounding rock of the arch crown,resulting in large settlement.When the rock mass is excavated,the residual surrounding rock corner is prone to stress concentration,which leads to the instability of local surrounding rock.Inverted arch can effectively limit the deformation of surrounding rock,it can reduce the internal stress of surrounding rock in order to increase the overall stability of the tunnel.