State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology,Shandong University of Science and Technology
College of Safety and Environmental Engineering,Shandong University of Science and Technology

为研究煤岩细观结构特征随着轴向应力增加的演化规律,利用 NanoVoxel-3502E X 射线三维显微镜与 Deben 原位加载实验台进行煤岩单轴压缩试验,获取不同应变条件下的 CT 数据,并结合三维可视化软件 AVIZO,研究煤样试件的孔隙裂隙分布特征,统计分析煤样试件孔隙裂隙细观参数-球形度、配位数、曲率和开度。揭示了煤样在单轴压缩情况下的细观结构空间分布特征及随时间的展布规律,细观结构随轴向应力的演化规律。研究表明:微小裂隙在 20~732 N 过程中大量出现,孔隙增多,在 431~732 N 过程中孔隙球形度集中分布范围变窄,部分孔裂隙逐渐融合进入裂隙网络,部分孔裂隙被压实压密,732 N 时部分孔隙被压实压密,导致孔裂隙减少 90 000 个,裂隙曲率逐渐增大、裂隙逐渐开度变大,配位数集中率更高,同时也说明煤样内部连通性更好,732 N 是裂隙网络发育的巅峰。轴向力达到 1 100 N(峰值)时,形成复杂的裂隙网络。随着单轴压缩过程的推进,部分孔裂隙虽然在 732 N 被压实压密,但由于轴向力的增大以及残余荷载的作用,孔裂隙的增多是必然趋势,峰值和峰后仍然存在微小孔裂隙,但峰后裂隙较窄,球形度更多的是集中在 1.5~2.0。贯通裂隙的曲率在裂隙网络的边缘普遍较高,即裂隙网络边缘为裂隙发育带。为研究煤样的时空演化规律提供了一种可行的技术手段,对于阐释煤岩细观结构时空演化过程具有实际意义。

In order to study the evolution of the microstructure characteristics of coal with increasing axial stress, this paper used NanoVoxel-3502E X-ray three-dimensional microscope and Deben in-situ loading test rig to carry out uniaxial compression tests of coal to obtain CT data under different strain conditions, Combined with the three-dimensional visualization software AVIZO, extracted the pores andfractures of the coal sample, studyed the pore and fracture distribution characteristics of the coal sample, and statistically analyzed the microscopic parameters of the number of pores, sphericity, and coordination number, curvature, thickness and other meso-structure parameters. It revealed the spatial distribution characteristics of the mesostructure of the coal sample under uniaxial compression and its distribution law over time, and the evolution law of the mesostructure with the axial stress. Studies have shown that small fractures appear in largenumbers from 20 N to 732 N, and the number of pores increases. During the process from 431 N to 732 N, the concentrated distributionrange of pore sphericity became narrower. Some pores and fractures gradually merged into the fracture network, and some pores and fractures were compressed. Part of the pores were compacted at 732 N, resulted in a reduction of 90,000 pores. The curvature of the fracturesgradually increased, the fractures gradually became thicker, and the coordination number concentration ratio was higher. It also showedthat the coal sample was internally connected. 732 N was the pinnacle of fracture network development. When the axial force reached 1 100N (peak), a complex fracture network was formed. With the advancement of the uniaxial compression process, although some pores andfractures were compacted at 732 N, due to the increase in axial force and residual load, the increase of pores and fractures was an inevitable trend, and there were still small pores and fractures after the peak, but the post-peak fractures were thinner, and the sphericity wasmore concentrated in 1.5-2.0. The curvature of the interconnected fractures was generally higher at the edges of the fracture network, theedges of the fracture network were fracture development zones. This paper provided a feasible technical means for studying the temporaland spatial evolution of coal samples, and has practical significance for interpreting the temporal and spatial evolution of the meso-structure of coal.

国家自然科学基金资助项目(52074171,51934004);泰山学者工程专项经费资助项目(TS20190935)

杨琪, 于岩斌, 崔文亭, 等. 单轴压缩下煤岩细观结构参数表征及演化规律[J]. 煤炭科学技术, 2023, 51(4): 88-95.

YANG Qi, YU Yanbin, CUI Wenting. Fracture evolution of coal under uniaxial compression based on X-ray microscopic imaging[J].Coal Science and Technology, 2023, 51(4): 88-95.