摘要
为了探究单轴应力加载过程中煤的天然裂隙结构演化规律及数学表征方法,基于计算机断层(computed tomography, CT)扫描试验,重构了能准确描述天然裂隙结构的三维数值模型,开展了煤样的单轴压缩数值模拟试验。引入长度、开度、裂隙度和分形维数表征裂隙空间形态,分析表征参数随载荷增加的变化规律,揭示了单轴应力加载过程中煤裂隙结构的演化特征。研究发现天然煤层内部多为小尺度裂隙,加载过程中裂隙演化可分为2个阶段:第一阶段,即加载初期,裂隙被压实闭合,对比未加载时,裂隙长度上限值下降44%,裂隙度下降35%,分形维数下降22%;第二阶段,随载荷增加,煤内部裂隙开始发育,峰值载荷时,长度平均上升10%,裂隙长度最小区间的分布频率上升12%,开度最小区间的分布频率上升50%。研究成果为揭示煤体在载荷作用下的裂缝扩展规律、有效实施水力压裂技术提供了理论依据。
In order to explore the evolution law and mathematical characterization method of natural fissure structure of coal under uniaxial loading, a 3D numerical model was reconstructed based on computed tomography(CT) scanning experiment to accurately describe natural fissure structure, and the uniaxial compression numerical simulation of coal was carried out. The length, opening, fissure degree and fractal dimension were introduced to characterize the spatial morphology of fissure, and the variation of characterization parameters with increasing load was analyzed. The results reveal the evolution characteristics of fissure structure of coal under uniaxial loading. The study shows that the coal is mostly composed of small-scale fissure, and the fissure evolution can be divided into two stages during the loading process. In the first stage, namely the initial stage of loading, the fissure is compacted and closed. Compared with the non loading, the upper limit of fissure length decreases by 44%, the fissure degree decreases by 35%, and the fractal dimension decreases by 22%. In the second stage, fissure in the coal begin to develop with the increase of load. At peak load, the length increases by 10% on average, the distribution frequency of the minimum interval of fissure length increases by 12%, and the distribution frequency of the minimum interval of fissure opening increases by 50%. The research results provide a theoretical basis for revealing the laws of coal fissure propagation under loading and effectively implementing hydraulic fracturing technology.
作者
杨永明
宁庚评
孙荣检
姜龙文
朱彦熹
YANG Yongming;NING Gengping;SUN Rongjian;JIANG Longwen;ZHU Yanxi(School of Mechanics and Civil Engineering,China University of Mining&Technology-Beijing,Beijing 100083,China)
出处
《中国科技论文》
CAS
北大核心
2023年第1期57-63,共7页
China Sciencepaper
基金
国家自然科学基金资助项目(51874309)
大学生创新训练重点项目(202106058)。
关键词
单轴应力
煤岩天然裂隙
三维重构模型
分形维数
量化表征
uniaxial stress
natural fissure of coal
3D reconstruction model
fractal dimension
quantitative characterization
