= 2 0.250 ( 21 17.5 )( 100 100 ) where: Ø effective = Effective diameter of the empty space E = Young's modulus of the rock mass (21.0 GPa) E0 = Reference Young's Modulus (17.5 GPa) REE = Relative energy of the explosive (ANFO = 100) The calculation determined a critical separation of 0.60m, a value that was taken as a maximum reference to define the drill mesh and the distribution of loaded holes around the cut. Finally, the design was validated through field tests focused on evaluating the effectiveness of the cut configuration under real operating conditions. These tests allowed adjusting the number of relief holes, as well as the delay times in electronic detonators, according to the load-relief ratio proposed by Holmberg, establishing the optimal conditions to maximize advance and minimize overbreak in 28-foot faces. Figure 12 – Proposed cut design considering a 102mm pilot center hole. ii. Holes Deflection Analysis The execution of 8-meter horizontal drilling in development faces represents a significant technical challenge, due to the possible deviation of the holes from their theoretical trajectory. Despite the use of high-precision equipment and the application of good operational practices, there are geological factors inherent to the rock mass, such as fractures, planes of weakness or abrupt lithological transitions, which directly influence the final direction of the holes. These deviations affect the geometry of the blast face, altering the symmetry and distribution of the drilling scheme at the bottom of the face. Consequently, it is difficult to 0.90m. 0.30m. 0.90m. R1 R2 R3 R4 R5 R6 R7 A1 A2 A3 A4
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