基于三维节理网络模拟的坝基岩体结构分类研究

以金沙江白鹤滩水电站左岸坝基岩体为研究对象，开展了基于三维节理网络模拟的坝基岩体结构分类研究。根据节理的分组分布和密度分布进行统计均质区分段，以分段为单位建立基于统计学和概率论的三维节理网络模型。在三维节理网络模型的模型正面、模型侧面和模型顶面上分别沿形心等角度布置模拟测线，将3个正交平面上54条模拟测线的RBI均值定义为三维等效岩体块度指数RBI3D，以RBI3D作为评价指标开展坝基岩体结构分类。结果表明：左岸第10梯段坝基岩体的完整性相对较好，其中整体块状占53.3%，块状占26.7%，次块状占20.0%，分析结果与实际地质情况相符。该方法充分考虑了节理分布的空间各向异性，并采用单一定量指标作为岩体结构的分类依据，兼顾了科学合理性和工程实用性。

Classification of rock mass structure of dam foundation based on 3D joint network simulation

Based on the 3D joint network simulation, the structure classification was carried out on the left bank dam foundation in Baihetan hydropower station on Jinsha River. Firstly, the dam foundation was separated into several statistical homogeneous subsections, according to the group distribution and density distribution of joints. Then, a 3D joint network model was established for each subsection by considering the statistics and probability theory. Secondly, uniform angle rotating measuring-lines were arranged on the positive, side and top surfaces of the model, respectively. Subsequently, a certain RBI value of each line and 3 rose diagrams for each orthogonal surface were obtained. Finally, the mean value of these RBIs from 54 measuring-lines was defined as 3D equivalent rock mass block index RBI3D. Moreover, the RBI3D, as an evaluation index, was used to classify the structure of dam foundation. Results showed that the integrity of No.10 bench in the left bank was relatively good. It was found that the ratios of the whole blocky structure, blocky structure and sub-blocky structure were 53.3%, 26.7% and 20.0%, respectively. The analytical results agreed well with the actual situation. Therefore, the presented method has been proven to be scientific rationality and engineering practicability, as the space anisotropy of joint distribution was fully considered and a single quantitative evaluation index was employed to determine the rock mass structure type.