含原生隐性节理工程岩体分级方法

白鹤滩水电站柱状节理玄武岩体内原生微裂隙发育,分布有宏观肉眼不易辨认的隐性节理,节理面较平整,多呈闭合状,为断续镶嵌结构,但岩石强度大,纵波波速高,岩体本身质量及其实际结构特征与测试得到的物理力学性质不相匹配。以白鹤滩水电站坝基柱状节理玄武岩作为含原生隐性节理的代表性岩体,基于其特殊性状,开展现场钻孔取芯、声波测试与点荷载试验,采用目前较为常用的几种工程岩体分级方法对其开展分级研究,对比分析岩体分级的结果与工程实际情况是否具有一致性;并以BQ分级方法为基础,在特定条件下引入RQD来修正岩体完整性系数K_v值,建立了一种适用含有原生隐性节理的工程岩体分级方法;将该方法用于白鹤滩柱状节理玄武岩的工程分级,分级结果与工程实际具有较好的一致性;最后,通过现场原位岩体变形试验对改进的分级方法进行验证可知,测试得到的柱状节理玄武岩变形参数与改进后BQ法的分级结果具有较好的匹配性。

Classification Method for Engineering Rock Mass Containing Primary Implicit Joint

Primary microfractures develop in the columnar jointed basaltic rock mass of Baihetan hydropower station, with implicit joints that can hardly be observed by naked eye. The joints are flat and closed in an intermittent mosaic structure; but the rock strength is high with large longitudinal wave velocity, resulting in the inconsistency between the tested physical and mechanical properties and the mass of rock mass as well as its actual structural characteristics. In view of this, in-situ core drilling, sound wave test, and point load test were conducted on columnar jointed basalt as a representative rock mass containing primary implicit joints. Several commonly used methods were employed to classify the quality of the rock mass, and the results were compared with actual engineering results.Furthermore, an improved classification method for engineering rock mass with primary implicit joints was proposed based on the BQ classification method to modify the K_v value by incorporating RQD under specific conditions.The proposed method was applied to the engineering classification of columnar jointed basaltic rock mass at Baihetan hydropower station, and the classification result agreed well with engineering practice.Finally, the method was verified through in-situ rock deformation test, and the results demonstrated that the classification result of the improved BQ method consisted well with the measured deformation parameters.