Experimental and numerical investigation of groove-assisted impact rock-breaking

Abstract

Groove-assisted impact rock-breaking represents a critical mechanical method for fracturing rocks; however, comprehending its underlying mechanisms governing fracture initiation and propagation remains incomplete. This paper aims to fill this knowledge gap by first establishing a dedicated test bench for groove-assisted impact rock-breaking and conducting double-impact head experiments with varying spacings. Subsequently, a finite discrete element method (FDEM) model is developed, incorporating zero-thickness cohesive elements, to validate and refine the numerical simulations against experimental outcomes. The investigation then systematically explores the impacts of double-head and multi-head rock-breaking to elucidate the dynamic evolution of stress fields and damage processes throughout the rock-breaking sequence. This includes the formation of dense cores, the initiation and propagation of fractures, and the eventual propagation of splitting damage. Noteworthy findings of this study include the identification and characterization of four distinct damage zones: an intermediate impact breakage zone dominated by shear damage, an annular extrusion damage zone typified by tensile failure, a primary surface cracking damage zone, and an interconnecting damage zone between dual impact heads, both characterized by tensile damage. Additionally, the study examines variations in penetration depth relative to the number and positioning of impact heads under conditions of equal energy input. These insights significantly enhance our understanding of the fracture mechanics involved in groove-assisted impact rock-breaking and lay the groundwork for enhancing rock-breaking efficiency.