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In underground engineering, rockburst caused by high ground stress pose a serious threat to the safety of personnel and equipment. Destress blasting has emerged as a promising method for mitigating rockburst risks. However, traditional analysis methods for destress blasting often overlook the physical processes involved. This paper introduces a discrete element method for destress blasting analysis that considers the dynamic evolution of explosion cracks influenced by geo-stress. In this method, three stages (i.e., opening, compressing and closing) were modeled through the dynamic evolution of stiffness of explosion cracks. Based on this method, the mechanism and influencing factors of destress blasting in the tunnel face were analyzed. The results indicated that explosion cracks induced by destress blasting can induce the release and transfer of strain energy. Based on variations in strain energy at different distances from the crushing zone, rocks outside the zone are categorized into stress relief, stress concentration, and undisturbed zones. The distributing character of strain energy implies that the spacing between destress blasting holes has a crucial influence on the destress effect: as the spacing of the destress blasting hole decreases, the effect of destress blasting can be divided into three stages (i.e., independent action stage, superposition action stage and coupling action stage), therefore, inappropriate spacing can increase rather than reduce the risk of rockburst. Furthermore, the proper arrangement of destress blasting holes can promote the preconditioning effect by eliminating the stress concentration zone. These results not only enhance understanding of tunnel face preconditioning processes but also offer insights for designing destress blasting strategies in high geo-stress conditions.
Yao et al. (Wed,) studied this question.