Dynamic mechanical properties of granite containing holes under impact loading

DAI Jun; LIU Boyuan

doi:10.16186/j.cnki.1673-9787.2024070095

Abstract：Objectives The study aims to investigate the dynamic mechanical behavior and failure mecha-nisms of granite containing cavities under impact loading,a critical issue during tunnel excavation and deep mine roadway development,where rock masses with voids are prone to dynamic disturbance-induced failure.Methods Granite specimens with different hole diameters were fabricated using waterjet cutting.Im-pact tests were conducted using a 50 mm diameter split Hopkinson pressure bar(SHPB)system.A dy-namic strain gauge recorded the stress-strain data,and a high-speed camera captured the failure process.The effects of hole size on dynamic mechanical properties and failure modes were analyzed.Results As hole diameter increases,the dynamic compressive strength decreases,while the peak strain increases.Hole di-ameter shows a positive correlation with both specific absorbed energy and specific reflected energy,and a negative correlation with transmitted energy.Larger holes induce more prominent major cracks and exhibit a clearer trend of promoting and then inhibiting horizontal crack propagation.More stress wave energy is ab-sorbed,accelerating internal fracture development and producing more debris upon failure.In small-hole specimens,strength is more sensitive to hole size than strain,while in large-hole specimens,strain is more sensitive.Small-hole specimens endure higher stress before failure but exhibit fewer precursors,re-sembling brittle failure,whereas large-hole specimens demonstrate behavior closer to ductile failure.Con-clusions This study reveals how hole size affects the dynamic compressive strength,energy dissipation be-havior,and failure evolution of granite under impact loading.These findings provide theoretical support for evaluating surrounding rock stability and designing anti-blast support systems in deep underground engineer-ing.