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首页> 外文期刊>Engineering Geology >A new perspective for the directivity of Rock Quality Designation (RQD) and an anisotropy index of jointing degree for rock masses
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A new perspective for the directivity of Rock Quality Designation (RQD) and an anisotropy index of jointing degree for rock masses

机译：岩石质量指定（RQD）直观性的新视角，以及岩体的连接度的各向异性指标

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摘要

The Rock Quality Designation (RQD) index is defined as the percentage of the borehole core or scanline that consists of intact lengths = 0.1 m, and has been widely used as an engineering measure of the jointing degree of a rock mass. The directivity of RQD, which means the value of the RQD obtained from drilling cores or scanlines with different orientations can be different for a given site, is usually regarded as a drawback by researchers and engineers. This study presents a new perspective for the directivity of RQD: the directivity of RQD should be regarded as an advantage of the index because it essentially reflects the anisotropy of rock masses. Because a smaller value of the RQD index implies a better reproduction of the different jointing degrees of different rock masses, its minimum value is selected as the representative RQD (RQD,), and its corresponding direction is called as the representative direction of RQD. In this study, to obtain the RQDr and its representative direction, theoretical formulas are derived to calculate the RQD in any direction based on some known RQDs in different directions. The proposed formulas consider the variance of the discontinuity orientations and sizes for a discontinuity set, use the traditional concept of RQD, and possess the associated simplicity; they only require sampling a few additional discontinuity orientations. Therefore, the proposed approach is easy to understand and apply in engineering practices. An anisotropy index of jointing degree (Mid) is defined to quantitatively describe the anisotropy of jointing degree for rock masses. The range of Mid is from 0 to 100, and the larger value of AI(jd) reflects stronger anisotropy of jointing degree of a rock mass. In this study, a hypothetical three-dimensional discontinuity network is constructed by performing Monte Carlo simulations, based on which the generated data are analyzed to validate the proposed method. The comparison between the calculated and actual values of the RQD shows that (a) the difference between the calculated and actual values of the RQD is 4 for 86.0% of the 1368 scanlines examined with respect to 12 scanline groups, except SG4-1 group, for which the proportion is 66.2%; (b) the difference between the calculated and actual values of the RQD is 6 for 96.2% of the 1368 scanlines examined with respect to 12 scanline groups, except SG4-1, for which the proportion is 86.7%; and (c) the proposed method of calculating the RQD in any direction based on some known RQDs in different directions is satisfactory. In addition, the comparisons show that the calculated RQD(r) and representative direction exhibit a good agreement with the actual results, and hence, the proposed method for this purpose is satisfactory. Moreover, an actual rock mass of a slope around the Qingshan Lake National Forest Park in China is investigated, and the results show that the proposed method is valid for that rock mass.
机译：岩石质量指定（RQD）指数被定义为由完整长度和GT组成的钻孔核心或扫描线的百分比。= 0.1米，并且已被广泛用作岩石块的连接度的工程测量。 RQD的方向性，这意味着从钻孔或具有不同取向的扫描线获得的RQD的值可以对给定站点不同，通常被认为是研究人员和工程师的缺点。本研究提出了RQD指令的新视角：RQD的方向性应该被视为指数的优势，因为它基本上反映了岩体的各向异性。因为RQD索引的较小值意味着更好地再现不同岩体的不同接合度，因此选择其最小值作为代表性的RQD（RQD，），并且其对应的方向被称为RQD的代表方向。在本研究中，为了获得RQDR及其代表方向，得出理论公式以基于在不同方向上的一些已知RQDS的任何方向上计算RQD。该拟议的公式考虑了不连续定向和尺寸的不连续定向和尺寸的方差，使用RQD的传统概念，并具有相关的简单性;它们只需要采样一些额外的不连续性方向。因此，拟议的方法易于理解并适用于工程实践。连接程度（中间）的各向异性指数被定义为定量描述岩体的连接度的各向异性。 MID的范围为0至100，并且AI（JD）的较大值反映了岩体的连接程度的更强的各向异性。在该研究中，通过执行蒙特卡罗模拟来构造假设的三维不连续网络，基于该研究基于所产生的数据来验证所提出的方法。 RQD的计算和实际值之间的比较显示（a）RQD的计算和实际值之间的差异是＆ 4对于＆除了SG4-1组之外，关于12个扫描线组检查的1368个扫描线中的86.0％，比例为66.2％; （b）RQD的计算和实际值之间的差异是＆ 6为＆除了SG4-1之外，对12个扫描线组检查的1368个扫描线中的96.2％，该比例为86.7％; （c）基于不同方向上的一些已知RQDS在任何方向上计算RQD的所提出的方法是令人满意的。此外，比较表明，计算的RQD（R）和代表方向与实际结果表现出良好的一致性，从而达到此目的的方法是令人满意的。此外，研究了中国青山湖国家森林公园坡度的实际岩石质量，结果表明，该方法对该岩石有效。

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