The mean discontinuity spacing can significantly varies with varying the scanline direction. To clarify the assessment of mean discontinuity spacing using measurement and relevant conventional equations, several artificial cubic models having three different discontinuity sets with various spacings and orientations were made by foam. The grand mean measured discontinuity spacing (X_GMM) of various scanline directions on different profile planes had a linear correlation with the block size (X_BS) of the typical artificial models (X_GMM = 0.725X_BS). Then, a new method using image analysis of in-situ rock mass was applied to assess mean rock mass block size as an alternative solution to represent the mean discontinuity spacing. The scaled images were prepared from ninety-four cases of twenty zones of in-situ rock masses in several mines, and the discontinuity spacing was also measured in six scanline directions for each case, as measurement was carried out in 564 scanlines. The images of in-situ rock masses were analyzed by Split-Desktop software and rock block size distribution, X₂₀, X₅₀ (mean size) and X₈₀ were determined. The rock block size obtained by the images analysis (X_{50-image analysis}) had a good linear correlation with the grand mean measured discontinuity spacing of six scanline directions of each case (X_GM-measured) for various rock mass conditions (X_GM-measured = 0.70X_{50-image analysis}). The obtained relation can be a reliable solution to specify the mean value of discontinuity spacing using image analysis of rock mass.

平均不连续间距可以随着扫描线方向的变化而显着变化。为了阐明使用测量和相关常规方程式对平均间断间距的评估，通过泡沫制成了具有三个不同间断集，具有不同间距和方向的几个人工立方模型。在不同轮廓平面上，各个扫描线方向的不连续平均间隔（X _GMM）的测量值与典型人工模型的块大小（X _BS）呈线性关系（X _GMM  = 0.725X _BS）。然后，采用一种利用现场岩体图像分析的新方法来评估平均岩体块大小，作为代表平均不连续性间距的替代解决方案。从多个矿场中二十个原位岩体的94个案例中制备了比例缩放的图像，并且在564个扫描线上进行测量的同时，还针对每个案例在六个扫描线方向上测量了不连续性间距。用Split-Desktop软件分析原位岩体的图像，并确定岩石块尺寸分布，确定X ₂₀，X ₅₀（平均尺寸）和X ₈₀。通过图像分析获得的岩石块大小（X _{50图像分析}）与在各种岩体条件下（X _GM测量 = 0.70X _{50图像分析}）每种情况下六个扫描线方向（X _GM测量）的总体平均测得的不连续间距具有良好的线性相关性。所获得的关系可以是使用岩体的图像分析来指定间断间距平均值的可靠解决方案。