基于$lt;i$gt;J$lt;/i$gt;积分的颗粒煤岩单轴压缩下裂纹扩展研究

颗粒煤岩是由众多离散的煤岩颗粒组成的固态多层次多结构物质,具有煤岩与颗粒物质的双重性质,其裂纹扩展规律可以从煤岩力学特性和颗粒物质多尺度特性进行研究. 首先,从能量角度对线弹性材料受压破坏,裂纹扩展产生原因进行了阐述,指出线弹性阶段裂纹的扩展动力源自应变能的释放. 然后,通过物理实验和数值试验从宏观和细观两方面对颗粒煤岩受压破裂过程中裂纹扩展做了进一步研究,结果表明:颗粒煤岩完全破裂后,底部会形成一个锥形堆,裂纹的扩展随着煤岩颗粒粒径的减小而减缓,部分裂纹扩展会出现突变点,且裂纹无光滑性;由于煤岩颗粒粒径等引起介质的非均匀性对裂纹扩展有重要的影响,均质度系数越大裂纹起裂时间越晚,声发射能量释放在裂纹扩展的轻度、中度和深度三个不同阶段逐渐变得频繁、剧烈. 研究结果将有利于进一步研究岩土类颗粒材料受压破裂过程的裂纹扩展规律. 关键词： J积分')" href="#">J积分 颗粒煤岩 单轴压缩 裂纹扩展

Granular coal crack propagation study under uniaxial compression based on J integral

Granular coal is a kind of multilayer and structured solid matter, which consists of a large assemblage of individual granular solids and has dual characters of coal and granular materials. Its crack propagation law can be studied using the coal mechanics and multi-scale characteristics. First of all, the linear elastic material may be damaged under compression; and the cause of crack propagation is explained from the viewpoint of energy that the dynamics of crack propagation is due to the release of strain energy. And then, further study on the granular coal crack propagation under uniaxial compression from macroscopic and microscopic raspects is carried out by physical experiment and numerical simulation. Results show that a cone is formed at the bottom of the heap, the crack propagation is slowed down with the decrease of coal particle size, mutation points in crack propagation will appear, and the crack will not be smooth after the granular coal is damaged completely. Besides, due to the influence of granular coal particle size, uniformity has an important effect on crack propagation. The greater the homogeneity coefficient, the later the fractures occur. The acoustic emission energy release becomes frequent and severe in the mild, moderate and deep stages of crack propagation. These results will be conducive to further study on the law of geotechnical granular materials crack propagation under compression.
Keywords： J integral circuit')" href="#">J integral circuit granular coal uniaxial compression crack propagation