温度冲击后煤岩的力学损伤特性研究

Research on Mechanical Damage Characteristics of Coal and Rock after Temperature Impact

温度冲击是提高煤岩透气性的重要手段。为研究温度冲击后煤岩力学损伤特性,采用高温-液氮热冷处理对试样进行单轴力学变形损伤破坏实验,探究不同温度冲击后煤岩损伤的声发射特征。结果表明:煤岩抗压强度和弹性模量随冲击温度的升高呈现非线性下降趋势,损伤强度降幅为34%~66%;弹性模量宏观上表征煤岩的损伤变量,拟合曲线呈现“下凹”特点;用声发射振铃计数从细观角度表征热冷作用后煤岩的损伤特性,冲击温差越大,煤岩损伤越明显,200℃-液氮冲击煤岩损伤达94%,此时煤岩致裂损伤效果最为显著。

Temperature impact is an important means to improve the permeability of coal and rock. In order to study the mechanical damage characteristics of coal and rock after temperature impact, a uniaxial mechanical deformation damage and damage experiment was carried out on the sample by high temperature-liquid nitrogen heat-cooling treatment, and the acoustic emission characteristics of coal and rock damage after different temperature impact were explored. The results show that the compressive strength and elastic modulus of coal and rock show a non-linear decreasing trend with the increase of impact temperature, and the damage strength decreases by 34%-66%;the elastic modulus macroscopically characterizes the damage variable of coal and rock, and the fitting curve shows the characteristic of "sag";the acoustic emission ringing counting is used to characterize the damage characteristics of coal and rock after thermal and cooling action from a mesoscopic perspective. The greater the impact temperature difference, the more obvious the damage of coal and rock. 200 ℃-liquid nitrogen impacted coal and rock damage up to 94%, at this time, the cracking damage effect of the coal sample is the most significant.