Investigation of the specific charge variations in determining the optimal methods for drilling and blasting of tunnels

two parameters of specific charge and specific drilling are used. Two
explosive substances, including ammonium nitrate and fuel oil
(ANFO) and Amulet, are used to charge the holes located on the
cross-section of the tunnels in order to advance by 3 meters. Also, the
cross-section of the selected tunnels was 19, 28, 32, 40, 48, 50, 65,
and 76 square meters with horseshoe, circle and D-shaped. The
diameter of the explosive hole is 48 mm for the Norwegian method
and 51 mm for the two energy balance models and the Swedish
method to compare them. A total of 160 designs are prepared for
three types of limestone, sandstone and marl. The results obtained for
two parameters of specific charge and special drilling for the selected
rock material are completely opposite. Also, in the Swedish methods,
according to the Amulet, the values of the calculated parameters are
close to the energy balance model. Finally, according to the
geomechanical parameters of the rock, for the Swedish method and
the energy balance model in charging with amulet explosives, the
energy balance model and the Holemberg-Persson method are
proposed in the optimal design for the tunnel drilling and blasting
pattern. In addition, for the Norwegian method and the energy
balance model in charging the holes with ANFO, the energy balance
model is prior to the Norwegian method. The amount of stemming of
holes in different parts of the tunnel face is less for the Swedish
method than the Norwegian and energy balance models.