Fracturing characteristics of unconfined rock plate subjected to point-plate loading

Abstract

Key factors determining hob rock-breaking efficiency include hob penetration velocity, cutter spacing, rock strength, and surrounding rock characteristics. Using CAD and PFC codes, 3D mechanical analysis models were developed for single and double-hob rock-breaking. The effects of penetration velocity, cutter spacing, rock strength, and lateral constraints on the process were examined. Insights gained revealed the rock-breaking mechanism, its adaptability, and optimal blade spacing. Key findings encompass destructive load, crack penetration, and rock mass morphological changes. Rock damage shows a ‘Y’ pattern, influenced by mineral composition and weathering. Crack widths vary, with increased surface roughness from core to lateral surfaces. Lateral constraints positively correlate intrusion rate with damage area and stress concentration. The destructive load triggers stress field transitions, resulting in multiple fracture surfaces. Limited deformation under constraints causes multiple load peaks, exceeding compressive stress. The resulting blocks have larger, flaky structures with distributed cracks. Cutter spacing significantly affects block formation, with narrower spacings favoring flaky slag production. Optimal blade spacing inversely correlates with rock strength.