In open pit and quarry mining, improving the drilling rate efficiency is fundamental to decreasing a mine’s operational costs. Different rocks have different properties and drilling rates. Understanding the correlation between these factors facilitates the selection of the proper drilling equipment, optimizes operational parameters, and improves the processes down the line, resulting in higher financial returns. An anisotropy index can be used to define a rock’s structural characteristics among other things, which can help when accounting for the uncontrollable variables presented during drilling. A new paper in the International Journal of Geomechanics studies the relationship between the vertical drilling rate and horizontal drilling rate on marble rocks to develop a new drilling anisotropy index.
Researchers Mohammad Rezaei and Kamran Esmaeili sought to evaluate the effect of rock anisotropy during drilling operations. In their study, “The Anisotropy of Rock Drilling in Marble Quarry Mining Based on the Relationship between Vertical and Horizontal Drilling Rates,” the authors conducted both field and laboratory experiments on drilled rock blocks. This study will help improve the effectiveness of rock drilling and optimize drilling costs. Learn more about this research at https://doi.org/10.1061/IJGNAI.GMENG-9658. The abstract is below.
Abstract
There is a high correlation between rock engineering behavior and the anisotropy index, which is crucial for the safety assessment of rock properties. In rock drilling, rock anisotropy significantly affects the cost and efficiency of the drilling project. Therefore, the anisotropy during the rock drilling process is investigated in this study. First, measurements of horizontal and vertical drilling rates were conducted at a marble quarry. Then, experimental tests were conducted to measure the physical and mechanical properties of collected minor rock blocks corresponding to the major under-drilling marble blocks. Through this process, a total of 40 data sets comprising vertical and horizontal drilling rates and 12 different rock properties were provided. The results showed that the vertical drilling rate correlates more with rock mechanical properties, while the horizontal drilling rate is associated more with physical characteristics. Also, sensitivity analysis confirmed that porosity and dry density are the most and least effective variables on both vertical and horizontal drilling rates, respectively. Based on the analysis of variance, the polynomial equation was found to be the optimum relationship between vertical and horizontal drilling rates. Based on the comparative analysis and using actual data sets, the accuracy of the proposed equation was proved. Finally, a drilling anisotropy index was proposed based on the ratio of vertical to horizontal drilling rates. The results showed that the drilling anisotropy index is more prominent in rock blocks with high-strength properties. Also, it was proved that the drilling anisotropy index has an inverse relation with vertical and horizontal drilling rates. As the vertical and horizontal drilling rates are inherently affected by different rock properties, it can be concluded that the suggested relationship between vertical and horizontal drilling rates and the proposed drilling anisotropy index could be effectively applied to assessing the interaction of drilling rates with rock properties in anisotropic rocks.
Learn more about this index and how you can apply it in the ASCE Library: https://doi.org/10.1061/IJGNAI.GMENG-9658.
