基于裂隙网络模拟的岩体RQD测量参数确定

Determination of Rod Measuring Parameters for Rock Mass Using Fracture Network Simulation

岩石质量指标(RQD)是国内外岩体质量分级体系中的重要指标,岩体工程中应用广泛。目前,地质工作者主要通过勘察阶段的钻孔取芯编录获得RQD。由于垂直于地表的钻孔以10 cm的阈值标准不能完全反映岩体结构的完整程度,RQD的工程应用具有明显的局限性。根据结构面实测数据,采用二维裂隙网络模拟方法进行RQD计算。通过测线模拟钻孔的方式在采样区内布置不同角度的测线,研究不同方向、不同阈值下的RQD变化规律。进一步通过改变测线的长度,明确测线长度与RQD取值的关系。结果表明:基于生成的岩体结构模型,不同阈值下的RQD计算结果得出该模型的最佳阈值为2.4 m;沿30°方向布置测线是获取RQD的最佳角度;在此基础上,测线长度在30 m时得到的RQD具有较好的代表性。确定岩体RQD测量的最佳阈值、最优布设方位以及最佳测线长度等参数可以充分反映了岩体结构的各向异性和尺寸效应,有效提高计算效率与结果的可信度,为具有强大的应用价值。

Rock quality designation(RQD)is an important index in the rock quality classification system,and it is widely used in rock engineering.At present,the geologists mainly obtain RQD through the core compilation of boreholes in the survey stage,and the engineering application of RQD has obvious limitations because the borehole perpendicular to the surface with a threshold standard of 10 cm which can not fully reflect the structural integrity of the rock mass.Based on the actual measured data of the structural surface,a two-dimensional fracture network simulation method is used for RQD.By arranging different angles of measuring lines in the sampling area by means of measuring lines simulating boreholes,the RQD variation regularity under different directions and different thresholds is studied.Further,the relationship between the length of the logging line and the RQD value is clarified by changing the length of the logging line.The results show that the RQD calculation results for different thresholds yield the best threshold value of 2.4 m for this model,and the best angle of RQD is to arrange the measurement line along 30°direction based on the generated rock structure model.Thus,the RQD obtained with a measurement line length of 30 m is more representative.Determining the optimal threshold value,optimal direction and optimal line length for rock body RQD measurement can fully reflect the anisotropy and size effect of rock structure,effectively improve the calculation efficiency and credibility of the results,and has strong application value.