定向断裂控制爆破下层理页岩的致裂机理  

Fracturing mechanism of bedding shale under directional fracture-controlled blasting

作　　者：杨国梁[1] 毕京九 董智文 赵桐德 赵建宇 赵康朴 YANG Guoliang;BI Jingjiu;DONG Zhiwen;ZHAO Tongde;ZHAO Jianyu;ZHAO Kangpu(School of Mechanics and Architectural Engineering,China University of Mining and Technology,Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《爆炸与冲击》2024年第6期1-15,共15页Explosion and Shock Waves

基　　金：国家自然科学基金(51934001)。

摘　　要：为探究定向断裂控制爆破下层理页岩的爆破致裂机理,采用切缝药包,对四种切缝角度下的页岩立方体试件进行爆破试验,采用数字图像相关技术(DIC)对页岩试件表面应变场的演化过程进行监测,分析了微裂纹孕育至宏观裂纹贯通的内在机理,并基于盒维数理论计算了不同切缝角度下页岩试件表面裂纹的分形维数,采用Matlab软件对爆后块度的筛分方法进行了编程分析,开发了全自动的粒径分析程序,实现了粒径圈定的可视化。试验结果表明:试件在不同比例爆距内的裂纹总密度与比例爆距之间存在负相关的幂函数关系,切缝方向与层理弱面的夹角对微观损伤区域出现的位置影响显著,当层理弱面与切缝方向平行时,损伤区域多集中于层理弱面处,对宏观裂纹的扩展路径影响显著,易于形成单一裂纹;层理弱面处的能量泄漏是造成页岩爆破破碎效果较差的重要因素,当切缝方向与层理弱面一致时,试件爆后的大块占比较高,爆后块度的分形维数平均值在各组间最低,仅为0.7843,而当切缝方向与层理面垂直时,试件的爆后块度分布较为均匀,爆后块度的分形维数平均值达到了2.5233,爆破破碎效果相对较好。The precise control of explosive energy to form an effective radial fracture network in shale is the key of shale gas dynamic extraction.In order to elucidate the damage and fracture mechanisms of shale under directional fracture-controlled blasting and establish a quantifiable relationship for shale damage and destruction under various blasting conditions,explosive tests were conducted on cubic shale specimens with four different fracture angles.The evolution of surface strain fields on the shale specimens was monitored using digital image correlation(DIC)technology.Additionally,the fractal dimensions of surface cracks on the shale specimens at different fracture angles were computed based on the box-counting theory.A programmed analysis of post-blast fragment size distribution was carried out using Matlab software,resulting in the development of a fully automated particle size analysis program with visual delineation of particle sizes.The experimental results demonstrate a negative power-law relationship between crack density and scaled distance within different scaled distances.The angle between the fracture direction and the weak plane of the bedding significantly influences the location of micro-damaged areas.Particularly,when the weak plane of the bedding is parallel to the fracture direction,damaged areas tend to concentrate along the weak plane,affecting the macrocrack propagation path and favoring the formation of a single crack.Energy dissipation at the weak planes of the bedding is identified as a crucial factor leading to suboptimal fracturing effects in shale blasting.When the fracture direction aligns with the weak plane of the bedding,a higher proportion of large fragments is observed in the post-blast specimens.The average fractal dimension of fragment size distribution is the lowest among all groups,measuring only 0.7843.Conversely,when the fracture direction is perpendicular to the weak plane of the bedding,the distribution of post-blast fragment sizes becomes more uniform.The average fractal di

关 键 词：页岩 爆破 裂隙场 数字图像相关技术 块度筛分程序 分形维数 

分 类 号：O389[理学—流体力学] TU452[理学—力学]