Dynamics of porous coal-rock masses subjected to blasting and impact loads on failure mechanisms and dynamic mechanical properties

Abstract

Under dynamic impact and blasting pressures, this investigation concentrates on the mechanical properties and failure mechanisms of soft coal-rock masses. The study follows a problem-methodology-results-application structure to systematically address these engineering challenges. In Huainan, China, we employed a custom experimental apparatus and a Separate Hopkinson Pressure Bar (SHPB) to conduct dynamic experiments on materials from the C13-1 soft coal seam, as well as its roof and floor, for blasting simulations. According to the findings, the dynamic compressive strength of coal, floor strata, and roof strata increases as the impact pressure increases. More specifically, the maximal strengths of these materials were 23.3 MPa, 16.9 MPa, and 6.57 MPa, respectively. These values are 3.3, 2.9, and 3.9 times their static compressive strengths. Superimposed damage zones and an increased risk of gas outbursts are the result of stress waves propagating and reflecting within coal fissures, as indicated by blasting simulations. It is imperative to implement effective safety strategies, including structural reinforcement and controlled pyrotechnic use, in order to mitigate these risks. The results enhance our understanding of the multi-scale mechanical behavior of coal-rock systems and provide valuable insights for the advancement of safer mining practices.