Theory and field tests of innovative cut blasting method for rock roadway excavation

Abstract

The primary factor influencing the blasting excavation speed of coal mine rock roadways is cut blasting. Traditionally, cut holes are positioned at the lower part of the section, leading to uneven minimum resistance lines for the subsequent row of auxiliary holes after blasting, which results in poor rock fragmentation. In this paper, an innovative concept that cutting area is similar to the rock roadway cross-sectional contour (CSRC) for cut blasting is proposed, which is composed of two parts: layout of cutting holes and charging structure. Firstly, the concept of CSRC is introduced and relevant theoretical models are established. Then, the CSRC cut blasting is studied through numerical simulation and model testing methods. Finally, the CSRC cut blasting and digital electronic detonators are applied on site. The results indicate that arranging cut holes using this method makes the shape of the cutting cavity similar to the cross-sectional profile. And the resistance line of the next row of auxiliary holes becomes uniform, thereby enhancing rock fragmentation near adjacent auxiliary holes. Additionally, the use of discontinuous charges in deep hole excavation significantly improves excavation efficiency and increases the extent of rock damage. The industrial test results further validate that adjusting the layout of cut holes mainly affects rock fragmentation uniformity, the number of boreholes, and the quality of the surrounding formation. Adjusting the charging structure mainly influences the efficiency and depth of blasting excavation. Compared to traditional methods, employing CSRC cut blasting technology significantly reduces the number of boreholes, improves production efficiency, and lowers costs.