Chen Liang, Li Junmeng, Zhang Dongsheng, Fan Gangwei, Zhang Wei, Guo Yachao
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, China.
School of Mines, China University of Mining and Technology, Xuzhou, China.
Sci Rep. 2022 May 5;12(1):7388. doi: 10.1038/s41598-022-11311-8.
The irregular shape of gangue blocks will affect the coordination structure between blocks in the crushed gangue accumulation body, and then affect the engineering mechanical properties of crushed gangue in the process of load-bearing compression. In this paper, through CT scanning experiment, particle flow numerical simulation experiment, and comprehensive application of image processing, 3D reconstruction, FLAC/PFC continuum-discrete coupling technology, the gangue digital 3D model and the numerical model of crushed gangue particle flow under triaxial compression condition considering the real shape of the block were obtained. The microscopic fabric evolution law and macroscopic deformation response characteristics of crushed gangue considering triaxial compression condition and different confining pressures were studied. The results show that: (1) the bearing capacity of crushed gangue materials increases with the increase of confining pressure; (2) the block aggregate in the gangue sample is gradually compacted, and the lateral deformation of the sample is changed from "extruding to the axis" to "bulging to the periphery"; (3) the vertical movement of the block decreases gradually from the top to the bottom of the sample, and there is a "triangle area" of block displacement at the top and bottom of the sample; the larger the confining pressure, the smaller the vertical displacement range at the top of the sample; (4) the process of "instability and failure-optimization and reconstruction" of skeleton force chain structure occurs constantly; as confining pressure increases, the stability of skeleton force chain structure and the bearing capacity of crushed gangue sample increases; (5) under the same strain state, the greater the confining pressure, the higher the fragmentation degree of the sample. This study reveals the internal mechanism of macro deformation of crushed gangue under the triaxial compression from the perspective of the mesoscopic fabric evolution. The research results are of great significance for the selection of crushed gangue in engineering application. In addition, the research results also have a significant impact on promoting the reasonable disposal and resource utilization of gangue solid waste and protecting the ecological environment of mining areas.
煤矸石块体的不规则形状会影响破碎煤矸石堆积体中块体之间的协调结构，进而影响破碎煤矸石在承载压缩过程中的工程力学性质。本文通过CT扫描试验、颗粒流数值模拟试验，并综合应用图像处理、三维重建、FLAC/PFC连续-离散耦合技术，获得了考虑块体真实形状的煤矸石数字三维模型以及三轴压缩条件下破碎煤矸石颗粒流数值模型。研究了考虑三轴压缩条件和不同围压下破碎煤矸石的细观结构演化规律和宏观变形响应特征。结果表明：(1)破碎煤矸石材料的承载能力随围压的增加而增大；(2)煤矸石试样中的块体聚集体逐渐压实，试样的侧向变形由“向轴向挤出”变为“向周边鼓胀”；(3)块体的竖向位移从试样顶部到底部逐渐减小，试样顶部和底部存在块体位移的“三角形区域”；围压越大，试样顶部的竖向位移范围越小；(4)骨架力链结构不断发生“失稳破坏-优化重建”过程；随着围压增大，骨架力链结构的稳定性和破碎煤矸石试样的承载能力增大；(5)在相同应变状态下，围压越大，试样的破碎程度越高。本研究从细观结构演化角度揭示了三轴压缩下破碎煤矸石宏观变形的内部机制。研究成果对工程应用中破碎煤矸石的选择具有重要意义。此外，研究成果对推动煤矸石固体废弃物的合理处置与资源利用、保护矿区生态环境也具有重要影响。
