以大山口水电站引水隧道为例,基于开挖卸荷理论,以径向应力卸荷量作为开挖卸荷分区,通过FLAC3D中fish语言模拟洞室开挖动态卸荷,计算了开挖围岩第一、第三主应力变化规律,基于卸荷应力分析,采用单元安全系数下降百分比描述围岩可能破坏形式,不同的等值线能较好地对应于3种不同破坏模式,对预测洞室开挖后可能的破坏模式有一定参考价值。 Taking the diversion tunnel of Dashankou Hydropower Station as an example, based on the theory of excavation unloading, taking the unloading of radial stress as the excavation unloading zone, the dynamic unloading of tunnel excavation was simulated by using FLAC3D fish, Based on the unloading stress analysis, the descending percentage of unit safety factor is used to describe the possible failure mode of surrounding rock. Different contour lines can correspond well to three different failure modes. After excavation possible damage patterns have a certain reference value.