Abstract Grasselli’s (2001) methodology on the quantification of the “shear-induced potential contact zones” is fundamentally very strong at properly dealing with the physics of the shear phenomenon. However, the high precision measurement system and the triangulation algorithm he used may not be easily accessible for everyone due to its industrial characteristics. Therefore, a simple technique called “the modified shear-induced potential contact zones” is introduced in the present work. By executing this technique on the surface coordinates of a large number of rock joints digitized through a specially developed mechatronic surface scanning device, “maximum possible and total potential contact areas” (A0 and Aθ*) and “directional surface parameters” (θ*max : maximum apparent dip angle, c2 : shape parameter, θ*max/c2 : change of angularity) are calculated in a specified direction. Ratio A0/c2 is proposed for a new directional roughness parameter. Surface roughness is also characterized by fractal dimension (Dtp), alternatively. Using a specially developed shear box, shear tests are performed in the direction of parameter calculation. Then, by a series of quantitative comparisons between the directional surface parameters and both the fractal dimensions and the shear strengths, the ability of the parameters to relate with the surface roughness and the shear strength is examined. In general, the results are satisfactory for the reliability of the modified technique. The main advantage of the introduced technique is its algorithmic simplicity facilitating direct applicability for basic 2D data sets, [z = f (x, y)], which can be practically acquired via easily accessible and cost-effective surface measurement systems. Additionally, another simple recipe is also introduced predicting contact zones visually prior to shearing. Then, total potential contact areas predicted in the shear direction are visually compared with the actual images of contacts observed in the tests. The best match is obtained when the threshold apparent inclination (θ*cr) is chosen equal to the experimental dilation angle (id) unique for the applied normal load. This clearly proves the validity of Grasselli’s (2001) “threshold apparent dip angle” concept.

中文翻译：

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通过三角棱镜表面积法算法计算方向相关的关节表面参数：理论和实验研究

摘要 Grasselli (2001) 关于“剪切诱发的潜在接触区”的量化方法在正确处理剪切现象的物理学方面从根本上非常强大。但是，他使用的高精度测量系统和三角测量算法，由于其工业特性，可能不是每个人都能轻松获得的。因此，在目前的工作中引入了一种称为“改进的剪切诱导电位接触区”的简单技术。通过在通过专门开发的机电一体化表面扫描设备数字化的大量岩石节理的表面坐标上执行该技术，“最大可能和总潜在接触面积”（A0 和 Aθ*）和“定向表面参数”（θ*max : 最大表观倾角, c2 : 形状参数, θ*max/c2 : 角度的变化）在指定的方向上计算。为新的方向粗糙度参数提出了比率 A0/c2。或者，表面粗糙度也以分形维数 (Dtp) 为特征。使用专门开发的剪切箱，在参数计算方向进行剪切测试。然后，通过定向表面参数与分形维数和剪切强度之间的一系列定量比较，检查参数与表面粗糙度和剪切强度相关的能力。总的来说，结果对于改进技术的可靠性是令人满意的。引入的技术的主要优点是其算法简单，便于直接适用于基本的 2D 数据集，[z = f (x, y)]，这实际上可以通过易于访问且具有成本效益的表面测量系统获得。此外，还引入了另一个简单的方法，可在剪切之前直观地预测接触区域。然后，将在剪切方向上预测的总潜在接触面积与在测试中观察到的实际接触图像进行视觉比较。当阈值表观倾角 (θ*cr) 选择为等于所施加的法向载荷唯一的实验膨胀角 (id) 时，将获得最佳匹配。这清楚地证明了 Grasselli (2001)“阈值视倾角”概念的有效性。在剪切方向上预测的总潜在接触面积与在测试中观察到的实际接触图像进行视觉比较。当阈值表观倾角 (θ*cr) 选择为等于所施加的法向载荷唯一的实验膨胀角 (id) 时，将获得最佳匹配。这清楚地证明了 Grasselli (2001)“阈值视倾角”概念的有效性。在剪切方向上预测的总潜在接触面积与在测试中观察到的实际接触图像进行视觉比较。当阈值表观倾角 (θ*cr) 选择为等于所施加的法向载荷唯一的实验膨胀角 (id) 时，将获得最佳匹配。这清楚地证明了 Grasselli (2001)“阈值视倾角”概念的有效性。