Study on the Three-Dimensional Behavior of Blasting Considering Non-Uniform In-Situ Stresses Distributed along the Blasthole Axis

Abstract

For roof-cutting by blasting in the gob-side entry under an overhanging hard roof, studies on the impacts of in-situ stresses on the propagation of blast-induced cracks have typically focused on uniform stresses but ignored the effects of non-uniform in-situ stresses (NIS) distributed along the blasthole axis. Therefore, the distribution patterns of hoop stress and rock damage caused by NIS distributed along the blasthole axis were investigated using numerical modeling and theoretical analysis. The results illustrate that with the rising NIS for the cross section along the blasthole axis, the peak values of hoop compressive stress at the same distance from the blasthole’s center gradually increase, resulting in a nonlinear attenuation trend in the damage range of the rock. Consequently, the spacing between blastholes should be determined based on the average length of the primary cracks under the maximum confining pressure. Additionally, for the cross section perpendicular to the blasthole axis, as the lateral pressure coefficient increases from 0.25 to 2, the damage range in the vertical direction significantly decreases. This results in varying extents of blast-induced cracks within the coal pillar, providing a reference for the design of shallow-borehole crack filling.