压剪应力作用下含瓦斯原煤细观裂隙演化特征试验研究

 利用自主研发的煤岩细观剪切加载试验装置，开展压剪应力作用下含瓦斯原煤细观裂隙动态演化特征试验研究，描述瓦斯运移通道的形成过程并分析影响细观裂隙形态特征的因素。研究结果表明：裂隙演化为瓦斯入渗煤体并在煤体中运移提供通道；在瓦斯压力及压剪应力的共同作用下，煤体表面破碎、脱落，破碎区更容易演化出新的裂隙。原生裂隙和坚硬颗粒都对细观裂隙演化产生影响：原生裂隙处更容易演化出新裂隙，从而在局部区域形成H型裂隙结构，且新裂隙与原生裂隙交汇时发生移动错位；坚硬颗粒则使得裂隙分叉并绕过自身演化，使得张拉和剪切共同作用形成细观裂隙，裂隙分叉角度为10°～100°，分叉角离散性大；原生裂隙与坚硬颗粒都使得压剪过程中瓦斯在煤体中运移的数目增多。随着法向应力的增大，加上初始损伤和坚硬颗粒的影响，裂隙分布率增大，煤体表面破碎越剧烈。

EVOLUTION CHARACTERISTICS OF MESO-CRACKS OF GAS-FILLED RAW COAL UNDER COMPRESSION-SHEAR STRESS

Using self-developed meso-shear test equipment for coal and rock containing gas，tests of raw coal containing gas under compression-shear stress were carried out to study the meso-cracks? dynamic evolution. The formation of gas migration pathways is described；and the factors influencing meso-morphological characteristics of cracks are analyzed. The results show that the evolution of cracks provides pathways for gas migration in coal continuously. Coal surface crushes and then drop as the gas pressure and compression-shear stress on coal simultaneously. The fractured zone has more initiations of cracks conversely. Both the horizontal original cracks and hard granules have effects on the meso-cracks；cracks initiate more easily when encounter the original cracks；then the newly formed cracks and the original cracks together make the composition of an H-shaped one locally. There is also always a dislocation for newly formed cracks subjected to the original cracks. The evolution directions of cracks change because of the existence of hard granules which are always bypassed，the bifurcation angles range from 10°–100° which shows obvious discreteness and meso-cracks are formed by tension and shear together. There are more pathways for gas migration as the existence of original cracks and hard granules. Both the fracture distribution rate and coal crushing extent increase as the normal stress increases and the effect of initial damages and hard granules.