热-应力耦合作用下不同粒径煤自燃氧化升温特性

Temperature rise characteristics of spontaneous combustion and oxidation of coal with different particle sizes under the effect of thermal-stress coupling

现有研究未考虑采空区中不同粒径煤会受到垮落煤岩和遗留煤柱产生的轴向应力的作用,致使煤的渗透率、裂隙结构等参数发生较大改变,进而影响煤自燃氧化升温进程。为研究热-应力耦合作用下不同粒径煤自燃氧化升温特性,利用荷载加压煤自燃特性参数测定装置和气相色谱仪,测定不同粒径煤的升温速率、耗氧速率和产热速率变化规律。实验结果表明:①不同粒径煤样在不同单轴应力下的升温速率随温度升高变化趋势具有一致性,整体上均呈先增高后降低趋势。当单轴应力为2,4,6,8 MPa时,随着煤样粒径增大,最大升温速率呈先增高后降低趋势;当单轴应力为10 MPa时,煤样最大升温速率随粒径增大而增高。②不同粒径煤样在升温过程中耗氧速率呈先快速增大后缓慢增大趋势;不同粒径煤样耗氧速率总体上均随单轴应力升高呈增大趋势。③不同粒径煤样在升温过程中产热速率整体呈先基本保持平稳再增大后减小趋势;随着煤样粒径增大,在适当的单轴应力作用下煤样最大产热速率会大于未施加单轴应力时。

The existing researches do not consider that coal of different particle sizes in the goaf is affected by the axial stress generated by the collapsed coal rock and the residual coal pillars,which will cause major changes in the coal permeability,fracture structure and other parameters,thereby affecting the temperature rise process of coal spontaneous combustion and oxidation.In order to study the temperature rise characteristics of spontaneous combustion and oxidation of coal with different particle sizes under the effect of thermal-stress coupling,the change law of the temperature rise rate,oxygen consumption rate and heat production rate of coal with different particle sizes is measured by using load-and-pressure coal spontaneous combustion characteristic parameter measuring device and a gas chromatograph.The experiment show the results as follows.①The temperature rise rate of coal samples of different particle sizes under different uniaxial stresses has a consistent trend with the increase of temperature,and the overall trend is to increase first and then decrease.When the uniaxial stress is 2,4,6,8 MPa,as the particle size of the coal sample increases,the maximum temperature rise rate first increases and then decreases.When the uniaxial stress is 10 MPa,the maximum temperature rise rate increases with the increase of particle size.②The oxygen consumption rate of coal samples with different particle sizes increases rapidly and then increases slowly during the temperature rise process.The oxygen consumption rate of coal samples with different particle sizes generally tends to increase with the increase of uniaxial stress.③The overall heat production rate of coal samples with different particle sizes tends to remain stable first and then increase and then decrease during the temperature rise process.As the particle size of coal samples increases,the maximum heat production rate of coal samples under appropriate uniaxial stress is greater than that without uniaxial stress.