煤矸石胶结充填体强度与细观结构的高温损伤效应

High-Temperature Damage Effect on Strength and Microstructure of Coal Gangue Cemented Filling Body

为了探究深部高温环境下胶结充填体的损伤规律,对煤矸石胶结充填体进行不同温度的高温加热处理,然后开展单轴压缩试验、计算机层析(CT)扫描试验和扫描电镜图像分析。试验结果表明,试件的抗压强度和弹性模量随温度升高而逐渐降低,且衰减速度在0~300℃范围内较快,随后逐渐变缓;二维CT图像表明,高温冲击作用使试件内部的裂隙数量和尺寸快速增加;由CT图像计算的试件孔隙率与环境温度呈正相关的指数型关系;在高温作用下,胶结充填体的内部孔隙、裂隙扩张与煤矸石颗粒接触关系均发生显著改变,这是导致试件强度衰减的根本机理。

In order to explore the damage law of cemented filling body in deep high-temperature environment,coal gangue cemented filling body was subjected to high-temperature heating treatment at different temperatures,followed by uniaxial compression test,computer tomography(CT)scanning test,and scanning electron microscopy image analysis.The test results show that the compressive strength and elastic modulus of the specimens gradually decrease with the increase of temperature,and the attenuation rate is faster in the range of 0300℃,and then gradually slows down.Two-dimensional CT images show that the number and size of cracks inside the specimen increase rapidly under high-temperature impact.The porosity of the specimen calculated by CT images is positively correlated with the ambient temperature.Under the action of high temperature,the internal pore and crack expansion of cemented filling body,as well as the contactD(V)T relationship between coal gangue particles have changed significantly,which is the fundamental mechanism leading to the strength attenuation of the specimens.