围岩动态演化与块体稳定性分析

Dynamic evolution and block stability analysis of surrounding rocks

以黄河上游拉西瓦水电站地下厂房为例,基于围岩动态演化和围岩应力的动态变化,运用块体理论分析了不同应力场状态下围岩块体的稳定性。研究结果表明,围岩块体稳定性、可能运动方式、滑动面(或滑面组合)以及滑动方向均显著地依赖于围岩应力场状态。在围岩动态演化过程中,拱顶块体的稳定性随着垂直应力σV增大和水平应力σh降低而减小,而边墙块体的稳定性逐渐增加,但当σV>σh则有所降低,反之亦然。应力状态的变化不仅影响块体稳定性,而且也使块体的滑动方式、滑动面、滑动方向发生变化。不同形态块体对应力状态的上述响应特征不同,短粗状块体反应更为明显。

Taking Laxiwa hydropower station which locates on the upper stream of the Yellow River as example, based on dynamic variation of surrounding rock stress, from viewpoint of dynamic evolution of surrounding rocks, the block stabilities under different stress fields are analyzed by using block theory. The results show that the stability, possible moving pattern, sliding plane or combined sliding plane and sliding direction of blocks are controlled by stress field of surrounding rocks. During dynamic evolution of surrounding rocks after excavation, the stability of crest blocks decreases with the increase of vertical stress try and/or the decease of horizontal stress σh, and vice versa. The stability of wall blocks increases with the increase of σv and/or the decease of σh, but decreases somewhat when σy 〉σh. The dynamic variation of stress field influences block stability, it also influences sliding mode, sliding plane and sliding direction of blocks. The above-mentioned stress effects on blocks with different shapes are different from each other. The shorter the block is, the stronger the stress effect manifests.