基于分形的岩体质量评价及广义RQD阈值确定

摘要

Discontinuity simulation was carried out based on the three-dimensional discontinuity network simulation technolo-gy. In the model establishment, cross-section parallel to the X, Y, Z planes are taken and the two-dimensional network of discontinuity is obtained. Then the fractal dimension of discontinuity distribution is computed by applying fractals to evaluate the rock mass quality. In the two-dimensional network diagram, simulated drilling is conducted by changing the threshold of gener-alized RQD and the RQD values under different thresholds are obtained. Studying the correlation between fractal dimension and RQD can provide basis for selecting an accurate threshold of RQD. The fractal dimensions of 3 cross-sections of a highway slope are calculated and the calculation results show that the RQD thresholds of 0. 2~0. 3 are reasonable.%基于三维结构面网络模拟技术,对采样区岩体优势结构面进行仿真模拟,在建立的模型中分别沿垂直于X,Y,Z轴方向切取剖面,得到各剖面的结构面二维网络图,运用分形理论分别计算其结构面分布的分形维数,进而对岩体质量进行评价。在上述网络剖面图中模拟钻孔,不断改变广义RQD的阈值,得到不同阈值下的RQD值。将各剖面的分形维数与广义RQD值对比分析,可以为准确选取广义RQD的最佳阈值提供依据。以某段公路边坡为例,当阈值在0.2~0.3时,广义RQD值与结构面分形维数吻合较好,故选取的RQD阈值应在0.2~0.3之间较为合理。