Effect of initiation pattern on rock damage and blasting seismic under multi-hole blasting

Abstract

In multi-hole blasting, the design of the initiation pattern is critical for the blasting effectiveness, but its effects on rock damage and blasting seismic are still unclear. This research focused on investigating the effect of initiation patterns under multi-hole blasting using numerical simulations and in-situ blasting experiments. First, the rock damage mode and blasting seismic characteristics under four initiation patterns were numerically studied. The rock damage degree was 19.26%, 13.42%, 17.06%, and 9.17% for the four initiation patterns, respectively. Correspondingly, the peak particle velocity (PPV) at monitoring point A reached 2.90 m/s in Case 1, but only 1.56–1.69 m/s in the other three cases. The results indicated the simultaneous initiation pattern causes more severe damage to the rock between blastholes and enhances blasting seismic effect. Furthermore, when the blasthole with a big explosive charge was preferentially initiated, the outcome of rock damage was improved. In-situ blasting experiments with various initiation patterns were conducted in a coal mine, and the blasting seismic was measured. The blasting seismic intensity is closely related to the blastholes number, explosive charge and spacing of blastholes. The simultaneous initiation pattern enhances both the PPV and source energy of blasting seismic, potentially causing rock bursts in the underground roadway. Finally, the practicable initiation pattern of deep-hole blasting in the coal mine was suggested.