Optimization of blasting hole density in rock roadway driving

In order to realize the rapid excavation of rock roadway, it is necessary to optimize the cutting structure and other blasting parameters of rock roadway blasting. On the basis of ensuring the blasting cycle footage and the surrounding quality of the roadway, it is necessary to reduce the number of full section blastholes and reduce the blasthole density. According to the data collected in the rock roadway blasting excavation site, the blasting parameters database of rock roadway excavation is established, which includes nine characteristic dimensions:construction time, mining area location, cutting mode, rock firmness coefficient, excavation section area, number of holes in the whole section, hole depth, explosive consumption and hole utilization rate. Through the linear fitting of the number of blastholes and cross-section area under the dimension of key parameters, the variation law of blasthole density of key parameters in different intervals is obtained. It is found that the blasthole density of most projects is about 5 per square meter, and there is a certain correlation between the blasthole density and various parameters. Among them, the fitting value of blast hole density of medium deep hole blasting is greater than that of shallow hole blasting; the blast hole density decreases significantly with the increase of explosive consumption; the blast hole density increases with the increase of blast hole utilization; the blast hole density of hard rock roadway is significantly greater than that of soft rock; the blast hole density of inclined hole cutting is greater than that of straight hole cutting. It is concluded that the high density of blast hole is affected by the mechanism of rock fragmentation and the limitation of blasting technology. Therefore, the improved blasting technology is proposed, that is, the second-order two-stage cutting technology and the directional fracture control technology of peripheral hole slotting cartridge. Through the field test, it is found that the directional fracture control technology of two-stage two-stage cutting and peripheral hole slotting charge can greatly reduce the blast hole density from 5 holes / m2 to 4 holes / m2, and ensure the blasting effect. It is of great significance to improve the rapid excavation level of rock roadway in China