岸坡倾倒变形体差异化发育机理研究

Study on the Mechanism of Differential Development of Slope Toppling Deformation

根据野外现场调查,某水电站上、中坝址区左右岸的倾倒变形现象存在巨大的差异,即右岸岸坡的倾倒变形无论是规模还是变形深度都比左岸大。针对两岸坡体倾倒变形差异化发育的问题,利用地质资料建立2个离散元模型,以分析倾倒变形的产生原因,并探究右岸发育的韧性剪切带和蚀变岩体对倾倒变形的影响。结果表明,相较于左岸,右岸坡体中有利的原生结构面是岸坡产生大规模浅层块状倾倒变形的控制性因素;不同高程的韧性剪切带和蚀变带构成软弱基座,使岸坡产生压缩—倾倒—拉裂变形,进一步增大了左右岸坡倾倒变形之间的差异。

According to the field investigation, there is a huge difference in the toppling deformation in the left and right bank of mediumdam at a hydropower station, that is, the toppling deformation of the right bank slope is larger than that of the left bank, both in scale and depth. In view of the problem of differential development of toppling deformation on both banks, two discrete element models are established based on geological data to analyze the causes of toppling deformation, and to explore the influence of ductile shear zone and altered rock mass developed on the right bank on toppling deformation. The results show that, compared with the left bank, the favorable primary structural plane in the right bank slope is the controlling factor for the large-scale shallow block toppling deformation of the bank slope. The ductile shear zone and the alteration zone at different elevations form the weak base,which leads to the compression-toppling-tension deformation of the slope, and further increases the difference on toppling deformation between the left and right bank.