冲击荷载下白云岩块度分布及分形特征  

Block size distribution and fractal characteristics of dolomite under impact loads

作　　者：秦梨 邓涛[1] 张成良[1] 廖元欢 周成 Qin Li;Deng Tao;Zhang Chengliang;Liao Yuanhuan;Zhou Cheng(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093

出　　处：《化工矿物与加工》2023年第2期20-26,共7页Industrial Minerals & Processing

基　　金：四川省科技厅应用基础研究项目(2020YFS0545)。

摘　　要：岩石破碎块度与爆破作业成本密切相关,研究岩石块度分布和分形特征对于深入了解岩石破坏特性和指导爆破施工具有重要意义。以四川攀枝花某露天采石场现场所取白云岩试样为研究对象,利用分离式霍普金森压杆(SHPB)系统对5种冲击气压(0.5、0.6、0.7、0.8、0.9 MPa)作用下的试样进行冲击压缩试验,分析了试样的应力-应变曲线和破坏规律,通过筛分得出试样的块度分布特征,基于分形维数定量描述了试样的破碎程度,结果表明:试样的应力-应变曲线经历了4个阶段,分别为裂隙闭合阶段、弹性阶段、塑性变形阶段和峰后软化阶段;随着应变率的增加,试样的破坏范围由边缘逐渐向中心扩展,破碎块度由大块过渡为小块及粉末;试样的平均粒径与应变率密切相关,试样破碎后的平均粒径随着应变率的增加而减小;分形维数与应变率呈线性关系,随着应变率的增加,大粒径碎块质量分数逐渐降低,中粒径和小粒径碎块质量分数逐渐升高。The degree of rock fragmentation is closely related to the cost of blasting operation,studying the block size distribution and fractal characteristics of rock is important to understand the rock destruction characteristics and give instruction to the blasting operation.Taking dolomite samples from an open-pit quarry in Panzhihua,Sichuan province as the object of study,split Hopkinson pressure bar(SHPB)system was employed to perform impact compression test on samples under five impact pressures(0.5 MPa,0.6 MPa,0.7 MPa,0.8 MPa,0.9 MPa),thus the stress-strain curve and breakage law of the sample were analyzed.The block size distribution characteristics of the sample were resulted from screening,quantitative description of the fragmentation level of the sample was conducted based on fractal dimension.The results show that the stress-strain curve of the sample experienced four stages:fissure closure stage,elastic stage,plastic deformation stage and post-peak softening stage.With the increase of strain rate,the breakage scope expanded gradually from the edge to the center of the sample,and the block size was reduced from large to small and to fine particles.The average particle size of the sample was closely dependent on the strain rate,and the averaged particle size of the sample after breakage decreased with the increase of strain rate.The fractal dimension presents in linear with the strain rate.With the increase of strain rate,the percentage of the large size fractions dropped gradually while that of medium size fractions and the small size fractions went up.

关 键 词：动态冲击载荷 白云岩 破碎形态 分形维数 分离式霍普金森压杆 应变率 筛分 

分 类 号：TU452[建筑科学—岩土工程]