论文部分内容阅读
掌子面失稳是浅埋软弱地层大跨度隧道施工时面临的主要工程难题之一,以依托工程为研究对象,采用三维有限元就CRD开挖时掌子面失稳的产生原因、主要影响因素及需要采取的应对措施等进行了研究,研究表明,掌子面地层软弱,挤出位移过大,易进入塑性状态导致掌子面稳定性问题突出;上、下台阶掌子面的中部为最容易失稳部位;上、下台阶岩体随着开挖面逐渐临近,球应力减小而剪应力逐渐增大,当与开挖面距离达到某临界值时,掌子面即进入短期稳定和不稳定状态。为有效防治掌子面失稳导致坍塌事故,必须对掌子面进行加固,且掌子面加固区长度应大于临界值。
The instability of the face is one of the major engineering problems in the construction of long-span tunnels with shallow depths and weak strata. Based on the project, the three-dimensional finite element method is used to analyze the cause of destabilization of face during CRD excavation and the main influence Factors and the need to take countermeasures were studied, the study shows that the palm face layer is weak, the extrusion displacement is too large, easy to enter the plastic state led to the stability of the dough surface problems prominent; The most likely to destabilize the site; the rock level of the upper and lower steps is gradually approaching with the excavation face, and the ball stress decreases and the shear stress increases gradually. When the distance from the excavation face reaches a certain critical value, the face of the face enters short-term stability And unstable state. In order to effectively prevent collapse of the face due to collapse, the face of the face must be reinforced, and the length of the reinforcement zone of the face should be greater than the critical value.