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以重庆某原位扩建隧道工程为依托,结合设计、勘察等资料通过数值模拟软件建立隧道三维模型,对隧道扩建施工过程中的地表沉降、隧道变形、围岩受力等进行了计算分析。计算结果表明,隧道扩挖完成后地表沉降槽向远离既有隧道侧略有偏移,呈现不对称性;隧道扩挖使隧道洞周左侧测点位移明显大于右侧测点的位移,整个隧道表现出了明显的偏压状态;为定量判断和把握围岩中不同区域的危险程度,引入了围岩危险系数的概念,围岩危险系数呈蝴蝶形分布,危险性较大的区域主要集中在墙脚、拱脚以及上下台阶交接处靠近中支撑部分围岩,施工时应当予以重点关注。
Based on an original extension project in Chongqing, the 3D model of the tunnel was established by numerical simulation software based on the design and survey data. The surface settlement, the deformation of the tunnel and the stress of the surrounding rock in the process of tunnel expansion were calculated and analyzed. The calculation results show that the surface settlement trenches of the tunnel are slightly offset away from the existing tunnel side after the completion of the tunnel excavation, showing asymmetry. The displacement of the measuring point on the left side of the tunnel tunnel is obviously greater than the displacement of the right measuring point on the tunnel expansion. The tunnel shows obvious biased state. In order to quantitatively judge and grasp the dangerous degree of different areas in the surrounding rock, the concept of surrounding rock hazard coefficient is introduced. The danger coefficient of surrounding rock is in a butterfly shape, and the areas with high risk are mainly concentrated At the foot of the wall, the arch foot and the junction of the upper and lower steps near the surrounding rock of the middle support part, the construction should pay special attention.