摘要
为研究砂质泥岩在冲击载荷下的破碎分形特征,采用霍普金森压杆试验装置,对砂质泥岩试样开展冲击压缩试验,探究其在5级冲击气压和2种长径比下的应力-应变曲线特征和破坏形态,并引入分形维数量化破碎程度和破碎块度分布,分析分形维数与加载值、强度值和能量值的关系。研究结果表明:冲击载荷下砂质泥岩破坏演化主要分为裂隙压实段、以弹性变形为主的弹-塑性稳定段、以塑性变形为主的塑-弹性非稳定段、宏观破坏段4个阶段,对于冲击前长度20 mm砂质泥岩试样,在裂隙压实段试样被压缩至19.86 mm,压缩量为0.7%;冲击载荷下砂质泥岩试样呈劈裂破坏,且破碎块度分布具有较好分形规律,长径比0.4和0.8试样的分形维数与应变率、动态抗压强度、破碎耗能密度均呈正相关;相同冲击气压下,长径比0.4试样对应变率和动态抗压强度的敏感性较长径比0.8更强;当破碎耗能密度相同时,长径比0.4试样较长径比0.8的分形维数更大。研究结果可为砂质泥岩顶底板巷道的防冲治理提供一定理论参考。
To study the fragmentation fractal characteristics of sandy mudstone under impact load,the split Hopkinson pressure bar(SHPB)test device was used to conduct the impact compression tests on the sandy mudstone samples,and the stress-strain curve characteristics and failure modes under five-stage impact pressure and two length-to-diameter ratios were explored.Furthermore,the fractal dimension was introduced to quantify the fragmentation degree and the distribution of fragmentation size,and the relationship between the fractal dimension and the loading value,strength value,and energy value was analyzed.The results show that the failure evolution of sandy mudstone under impact load can be divided into the crack compaction section,elastic-plastic stable section dominated by elastic deformation,plastic-elastic unstable section dominated by plastic deformation,and macroscopic failure section.For the sandy mudstone sample with a length of 20 mm before impact,the sample is compressed to 19.86 mm in the crack compaction section,with a compression amount of 0.7%.Under the impact load,the sandy mudstone sample exhibits the splitting failure,and the fragmentation size distribution has a good fractal pattern.The fractal dimension of LD 0.4(length-to-diameter ratio of 0.4)and LD 0.8(length-to-diameter ratio of 0.8)is positively correlated with the strain rate,dynamic compressive strength,and fragmentation energy dissipation density.Under the same impact pressure,LD 0.4 has a stronger sensitivity to strain rate and dynamic compressive strength.Under the same fragmentation energy dissipation density,the fractal dimension of LD 0.4 is larger.The research results can provide certain theoretical support for the anti-erosion treatment of roadways with sandy mudstone roof and floor.
作者
孙卓越
吴拥政
周鹏赫
SUN Zhuoyue;WU Yongzheng;ZHOU Penghe(CCTEG Coal Mining Research Institute,Beijing 100013,China;Coal Mining and Designing Branch,China Coal Research Institute,Beijing 100013,China)
出处
《中国安全生产科学技术》
CAS
CSCD
北大核心
2024年第6期133-139,共7页
Journal of Safety Science and Technology
基金
中煤科工开采研究院有限公司科技创新基金(KCYJY-2023-QN-01)
国家自然科学基金面上项目(52174080,51974160)。
