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针对某水电站业已完成的地下厂房第一期开挖开展坚硬围岩初期支护的合理时机研究。首先,根据地下厂房围岩变形监测资料,研究分析了围岩位移变化率的时间效应及坚硬围岩的应力释放特征;其次,借助二维有限元分析软件Phase2,通过指定不同的应力释放系数来模拟不同的洞室支护时机,计算结果表明在不同应力释放阶段,围岩自承载能力和围岩变形均表现出阶段性发展的趋势;随支护时机推迟,支护应力减小,围岩塑性区和开挖变形量增大;同时考虑坚硬围岩应力释放的时间效应,研究围岩变形特征曲线,为初期锚喷支护的设置时机提供了可以测量、控制的研究手段。最后,综合不同支护时机下的支护抗力和围岩应力、变形分析表明:针对该水电站地下厂房坚硬围岩,应力释放达约60～70%或开挖通过施工断面15d左右是一个较为有利的支护时机。计算结果符合地下工程施工过程的一般规律,对于该水电站地下厂房正在进行的开挖支护活动具有很好的参考价值。
Research on the Reasonable Timing of Carrying out Initial Support of Hard Wall Rock in the First Stage of Underground Powerhouse Completion of Some Hydropower Station. First of all, based on the deformation monitoring data of surrounding rock of underground powerhouse, the time effect of displacement rate of surrounding rock and the stress release characteristics of hard rock are studied. Secondly, with the help of two-dimensional finite element analysis software Phase2, different stress release coefficients The results show that the self-bearing capacity of surrounding rock and the deformation of surrounding rock all show a stage-by-stage development trend at different stress release stages. With the delay of support time, the support stress decreases and the surrounding rock The plastic zone and the amount of excavation deformation are increased. Meanwhile, considering the time effect of stress release in hard surrounding rock, the deformation curve of surrounding rock is studied, which provides a measure that can be used to measure and control the timing of the initial bolting and shotcreting support. Finally, considering the support resistance and the surrounding rock stress under different support timing, the deformation analysis shows that it is more advantageous to deal with the stress of up to 60 ~ 70% of the rock mass or digging through the construction section for about 15 days in the hard rock of the underground powerhouse of the hydropower station Support time. The calculation results are in accordance with the general rules of the underground construction process and have a good reference value for the ongoing excavation and support activities of the underground powerhouse of the hydropower station.