大断面隧道挑顶施工三维数值计算分析

摘要

采用三维有限元数值计算的方法,对大断面隧道挑顶施工过程中力学场特征和变化趋势进行研究,根据围岩力学行为及分布规律,指导大断面隧道挑顶施工并总结开挖支护安全施工技术.在大断面隧道挑顶施工过程中,挑顶台阶上的支护结构强度和密度直接影响隧道围岩位移分布；斜井核心土的留设和加固可以有效改善洞室围岩受力情况；挑顶施工过程中,在斜井中对正洞核心土进行有效的注浆加固可以有效改善支护体系受力,减小应力集中程度.%By means of Three-dimensional finite element numerical method, mechanical characteristics and trends of the large section tunnel during the roof-ripping construction process are studied. According to the mechanical behavior and distribution of surrounding rock, the roof-ripping construction of large section tunnel is guided and the supporting and protecting techniques for excavation safety are summarized. In the course of roof-ripping construction of large section tunnel, the intensity and density of supporting structure on the steps directly affect the displacement distribution of surrounding rock; the preservation and reinforcement of the core soil in the sloping shaft can effectively improve the load capability of surrounding rock; the mechanical characteristics of supporting system can be effectively improved and the tress concentration can be reduced while the core soil of the tunnel are reinforced effectively by grouting in the sloping shaft.