Research on Roof Cutting and Pressure Releasing Technology of Cumulative Blasting in Deep and High Stress Roadway

Abstract

Affected by high in-situ stress and mining activities, In the original support scheme, entry of guotun coal mine is seriously deformed. The side of the head entry bulges out seriously and the roof sinks seriously. In order to solve the problem of large deformation of roadway, guotun coal mine adopts the technology of a nonpillar mining method with entry automatically retained in 4306 mining face. First, taking method of theoretical analysis, the stress model of blasthole under the deep condition is established, the mechanical conditions of crack propagation under the action of directional detonation wave and high surrounding rock binding force are obtained theoretically. Next, the mechanical model of roof cutting and pressure relief is established. Afterwards, The mechanical model of directional blasting under the condition of stress constraint is established by using LS-DYNA numerical calculation software, the evolution characteristics of effective stress and the law of crack growth are analyzed. In the end, the field test was carried out in 4306 mining face, and the blasting effect was observed by drilling peep, and the deformation of the head entry before and after pressure relief was monitored and analyzed. The results show that directional fracture blasting can produce a continuous crack, and the effect of pressure relief is remarkable, effectively controlling the deformation of surrounding rock under high in-situ stress.