570 For the technical evaluation, four cut tests were carried out, aimed at determining: • The optimal cutting scheme (type of cut). • The most suitable delay times for the firing sequence with electronic detonators. These tests allowed validating the behavior of the new strategy under real operating conditions, establishing a technical basis for its continuous application in development tasks with long drilling. 4. CUT TESTS i. Initial Cut Design From the design point of view, the most relevant considerations focused on achieving an effective feed of close to 8.0 m, using 54 mm diameter break holes and determining the optimal number of relief holes, which have a diameter of 102 mm. Since the drilling length is 8.0 m, the equivalent relief diameter was calculated using the mathematical model proposed by Holmberg (1982), according to equation (1): where: Ø equivalent = 110 + 15.4 x L (1) Ø equivalent = equivalent relief diameter (mm) L = Drill Length (m) Substituting L = 8.0 m, we get: Ø equivalent = 110 + 15.4 x (8) = 233.2mm With this value, the optimal number of relief holes is determined by equation (2): where: Ø equivalent = Ø relief x (2)√Å (2) Ø relief = 102 mm n = number of relief holes Clearing n, the value of 5.2 ≅ 6.0 is obtained, which satisfies the geometric condition of the relief necessary for the evaluated drilling length. Additionally, the relative empty volume (VR) generated by the relief and loaded holes was analyzed in relation to the effective breaking area. The expression used is shown in equation (3): _V= [° ]^_`,-./-0 a bc ad∅ ,- 2 ./-0e2f? [° ]^_`3,-45 a bc ad∅ 3, 2 -45e2f ghig678@ j[° ]^_`,-./-0 a bc ad∅ ,- 2 ./-0e2f? [° ]^_`3,-45 a bc ad∅ 3, 2 -45e2fk (3)
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