冲击作用下岩石破碎的动力学特性及能耗特征研究

摘要

In order to study the degree of difficulty of breaking rocks and the associated controls for dynamic breaking in percussion drilling ,a theoretical model based on the principal of damage due to inher‐ent defect .This model incorporated rock dynamic fracture strength ,breaking time and energy consump‐tion .Further ,the failure strength ,breaking time and energy consumption characteristics in the process of rock breaking were analyzed by means of the impact test on sandstone with the split Hopkinson pressure bar (SHPB) .Results indicate that calculating result with the theoretical model is basically consistent with the results from laboratory tests ,tand he relationship between the strain rate and three parameters as dy‐namic load strength ,breaking time and energy consumption of sandstone appears to be a power function . When the strain rate increases in the range from 60 s-1 to 115 s-1 ,the dynamic load strength is 1 .33 1.83 times higher than the static load strength ,and the breaking time decreases from 84 μs to 52 μs rapidly . Moreover ,the greater the strain rate and energy consumption ,the smaller the rock fragments .The re‐search results in this paper can provide a reference for evaluating the degree of difficulty in dynamic rock breaking and improving the rock breaking efficiency by using impact loads .%为了研究冲击钻井中岩石破碎的难易程度及动态破碎规律，基于固有缺陷的损伤原理，建立了岩石动态破裂强度、破碎时间和破碎能耗的理论模型，通过砂岩的霍普金森压杆冲击压缩试验分析了其破坏强度、破坏时间及破坏过程中的能量耗散特征。分析研究发现，试验结果与模型计算结果基本吻合，砂岩的动载强度、破碎时间和破碎能耗均与应变率之间呈幂函数关系，随着应变率在60～115 s－1范围内增加，砂岩的动载强度与静载强度相比增大了1．33～1．83倍，破碎时间从84μs迅速缩短至52μs ，且应变率越大，岩石破坏后的碎块尺度越小、破碎能耗值越大。研究结果可为衡量岩石动力破碎的难易程度及提高冲击破岩效率提供参考。