[Objective]The bedding plane location significantly impacts the dynamic failure processes and mechanical properties of coal-rock composites,but the specific influence patterns remain unclear.[Methods]Dynamic mechanical tests were conducted on coal-rock composite specimens with bedding planes located at the top,middle,and bottom us-ing the split Hopkinson pressure bar(SHPB).The investigation focused on the dynamic stress-strain behavior,failure process,energy distribution,and fragmentation characteristics under impact loading conditions.[Results and Conclu-sions]The findings indicate that:(1)The dynamic stress-strain behavior of coal-rock composites can be segmented into five distinct stages:near-linear stage,nonlinear dynamic stress-strain stage,elastic modulus reduction stage,macroscop-ic rupture stage,and stress wave unloading stage.(2)As the bedding plane location transitions from top to bottom,the extent of rock damage increases,the failure process becomes more pronounced,and the uniformity of post-failure frag-ments decreases.Conversely,the coal component exhibits a reduction in damage severity and an increase in fragment size after failure.(3)The presence of a bedding plane significantly reduces the dynamic compressive strength of coal-rock composites.Compared to composites without a bedding plane(average strength:79.487 MPa),the dynamic com-pressive strength decreases by 7.25%(average strength:73.724 MPa)when the bedding plane is at the top,by 22.26%(average strength:61.798 MPa)when at the middle,and by 18.24%(average strength:64.991 MPa)when at the bottom.(4)The energy distribution changes as the bedding plane location shifts from top to bottom,with a reduction in reflected energy,an increase in absorbed energy,and a decrease in transmitted energy.These results provide valuable insights for optimizing fracturing positions in large-scale hard roof treatment using ultra-long hole hydraulic fracturing or surface fracturing techniques.
维普
万方数据