煤层顶板砂岩在高温下的力学特性及破坏机理

Mechanical Characteristics and Cracking Mechanism of Coal Roof Sandstone under High Temperature

采用偏光显微镜、扫描电镜及岩石力学试验系统等仪器设备研究了煤层顶板砂岩在常温到1200℃范围内的力学特性和破坏机理。结果表明,煤层顶板砂岩在加热过程中强度急剧降低的温度与岩石内部裂隙形成和晶体形态变化的温度基本一致,说明岩石微观结构在高温下的变化对其力学特性有显著影响;煤层顶板砂岩中有机物在高温下的分解和析出,对砂岩中裂隙形成与发展具有一定的影响,该砂岩在高温作用下的破坏是晶体晶型转变和膨胀等产生的热应力及有机物析出共同作用的结果。

The Mechanical characteristics and cracking mechanismofcoalroofsandstoneunderroomtemperaturethe1 200 ℃ high temperature has been researched with a polarizing microscope , SEM and rock mechanical test equipment. The researches discovere that the temperature at which the strength of the sandstone decreased sharply during the sandstone was heated was the same as that of the crack forming in the sandstone and crystal form transition. The results indicated that the change of the sandstone microstructure under the high temperature affected obviously the mechanical characteristics of sandstone; the decomposition of organic matter in the sandstone and the migration of the decomposing products affected the forming and expanding of the cracks. The destroying of the sandstone under high temperature results from crystal form transition and crystal volumetric expansion, the migration of the decomposing products.