基于三维裂隙网络的RQD尺寸效应与空间效应的研究

 岩石质量指标(RQD)是岩土工程与地质工程中的重要概念，在岩体性质分析中起到了重要作用，但RQD存在着明显的尺寸效应与空间效应，这在以后岩体工程设计计算中并没有引起充分的重视。为研究RQD的空间效应，采用三维裂隙网络模拟方法模拟现场真实岩体，并在模型中设立大量测线获取岩体中不同位置的RQD值。结果表明，岩体中不同位置的RQD值并不相同，存在明显的空间效应。为获取可整体代表岩体好坏程度的RQD值，需在大量RQD样本的基础上进行分析。另外，为更好地体现岩体的非均质性，研究不同阈值下的RQD范围，最终确定可充分反映待分析岩体的最佳阈值，为4 m。尺寸效应是RQD参数的重要性质，通过改变测线长度的方法探讨RQD在不同尺度下的变化情况。总结、提出RQD的计算模型与公式，即：A-A模型、T-T模型、A-A-S模型、Priest-Hudson公式与Senz-Kazi公式。分别研究与对比不同模型下RQD的尺寸效应，结果表明，采用A-A-S模型可充分减少尺寸效应带来的RQD的计算误差；当阈值较大时，Priest-Hudson公式与Senz-Kazi公式存在一定的误差，基于三维裂隙网络模拟的方法进行RQD的计算将会更为准确。

STUDY OF SIZE EFFECT AND SPATIAL EFFECT OF RQD FOR ROCK MASSES BASED ON THREE-DIMENSIONAL FRACTURE NETWORK

Rock quality designation(RQD),which plays an significant role in the rock mass analysis,is an important parameter in geotechnical and geological engineering.However,the size effect and spatial effect have not been comprehensively considered.To investigate the spatial effect of RQD,three-dimensional(3D) fracture network modelling is used to simulate the actual rock mass,and numerous scan-lines are set to obtain RQD values.The result shows that the RQD values vary in different regions and have obvious spatial effect.To obtain the characteristics of RQD that could represent the whole rock mass quality,the analysis based on plenty of RQD samples should be conducted.In addition,to better reflect the inhomogeneity feature of rock mass,RQD ranges of different thresholds are studied;and the optimal threshold of 4 m that can comprehensively reflect the inhomogeneity feature of the investigated rock mass is determined.The size effect is an important feature of RQD.To investigate the feature,the RQD variation is researched by changing the scan-line length.The models and equations(i.e.A-A model,T-T model,A-A-S model,Priest-Hudson equation,and Senz-Kazi equation) are proposed and summarized.The size effects of different models are studied.The results show that:the error of size effect can be decreased using A-A-S model;when the threshold is relative large,the results by Priest-Hudson equation and Senz-Kazi equation have errors;and the RQD value based on 3D fracture network is more correct.