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长甸电站水下岩塞为我国首例超大直径岩塞,其平均直径达12.3 m且地质条件较为复杂,是该电站改造工程的重大技术难题之一。针对长甸电站进水口边坡岩体节理发育的特点,采用3DEC方法建立了节理岩体模型,对施工期集渣坑、连接段开挖导致的岩塞局部拉应力和非连续变形特征进行了分析,进而,基于强度折减法对爆破前期岩塞体的潜在失稳模式和稳定性分区进行了评价。研究表明,节理对岩塞体的稳定特征影响突出,岩塞体的潜在失稳模式呈现由洞内浅层向深部追踪节理密集带Jm7发展的趋势,岩塞掌子面局部拉应力区的块体稳定性相对最差;而考虑结构面的不同连通率的岩塞体整体安全系数在2.2~5.1之间,满足安全性要求。针对节理化岩塞体采用的3DEC模拟能够良好地反映结构面的控制性作用,分析方法可以为类似工程提供参考。
Changdian Subaqueous Submarine Rock Plug is the first ultra-large diameter rock plug in our country with an average diameter of 12.3 m and complicated geological conditions, which is one of the major technical problems of the power station renovation project. According to the characteristics of rock mass joint development of water inlet slope of Changdian Hydropower Station, the 3DEC method was used to establish the jointed rock mass model. The local tensile stress and discontinuity deformation of the rock plug caused by the excavation of the slag pit and connecting section during the construction period Then, based on the strength reduction method, the potential instability mode and stability zone of the pre-blasting plug body were evaluated. The results show that the joints have an obvious influence on the stability of the rock plug body. The potential instability mode of the rock plug body presents the trend of developing from the shallow depth to the deep tracking zone Jm7. The local tensile stress zone of the rock face While the overall safety factor of rock plug body considering different connectivity rates of structural plane is between 2.2 and 5.1, which meets the safety requirements. The 3DEC simulation applied to the jointed rock plug body can well reflect the controllability of the structural plane. The analysis method can provide reference for similar projects.