Effects of varying loading rates on the Brazilian splitting characteristics of coal-rock composites
Objectives To investigate the tensile characteristics of coal-rock composite structures during the mining process,the study takes coal-rock composite specimens as the research object.Methods Brazilian splitting tests were conducted on coal-rock composite specimens under varying loading rates using the RMT150B testing machine.The effects of loading rates on the strength characteristics,failure modes,en-ergy features,and crack evolution during splitting failure were analyzed.Results The stress-strain curves of the coal-rock composites generally followed four stages:compaction,elasticity,yield,and failure.The fai-lure mode was independent of the loading rate,with all specimens splitting along the interface of the disks.The tensile strength of the composite increased with loading rate,showing significant changes under low loading rates,while the rate of increase diminished as the loading rate became higher.The energy concen-tration in coal-rock composite specimens ranged from 0.33 J to 0.42 J,and higher tensile strength required greater energy for failure.The stress-crack strain curve exhibited three stages before the peak:crack clo-sure,elasticity,and crack propagation.The crack parameters demonstrated a pronounced dependency on loading rates.Conclusions These findings provide valuable theoretical insights into the tensile failure mecha-nism of coal-rock composite structures.
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