韧性剪切带和蚀变岩体对坡体卸荷特征影响分析

Influences of Ductile Shear Zone and Altered Rock Mass on Characteristics of Slope Unloading

岸坡异常卸荷是西南深切河谷地区进行大规模水电工程建设过程中常遇到的典型工程问题之一。根据野外详细地质调查,得出研究区坡体卸荷特征,再以是否考虑韧性剪切带和蚀变带为变量建立 3个二维离散元模型,模拟河谷 5次下切后坡体的变形情况,对比分析韧性剪切带和蚀变带对坡体卸荷特征的影响。研究结果表明:研究区卸荷异常主要与韧性剪切带和蚀变岩体的发育有关;韧性剪切带和蚀变带质软,其软弱基座效应和弱抗风化能力加剧了坡体变形程度,同时构成软硬相间的坡体结构,使得沿缓倾坡外结构面的差异剪切错动更为明显。相关成果可供从事高边坡坡体卸荷研究人员参考。

The abnormal slope unloading is one of the typical engineering problems encountered in large-scale hydropower project construction process in southwest deep valley area. Though field geological investigation, the characteristics of slope unloading was discovered, and three two-dimensional discrete element models were established to simulate the deformation of the slope after five times of valley incision to analyze the influence caused by ductile shear zone and the alteration zone on slope unloading characteristics under condition of considering ductile shear zone and the alteration zone or not. The results show that the anomalies of slope unloading is mainly related to the distribution of ductile shear zone and the alteration rock mass. The soft base effects and weak ability to resist weathering of the ductile shear zone and the alteration zone, which are weaker than normal rock mass in mechanical properties, exacerbate the slope deformation degree. At the same time, the hard and soft slope structure make the phenomenon different shear dislocation along the flat slope surface structure more apparent.