三轴加载煤体瓦斯渗流速度-温度联合响应特征

瓦斯渗流速度及温度响应能反映出受载煤体内部结构和能量的变化,可以作为煤与瓦斯突出预警信号。以型煤为研究对象,利用自主研发的含瓦斯煤受载破坏试验系统测定了三轴加载条件下煤体的瓦斯渗流速度及温度联合响应规律,分析了加载速率对瓦斯渗流速度和温度影响效应,建立了瓦斯渗流速度及温度与突出煤失稳破坏之间的关系。实验结果表明:(1)在整个加载过程中,瓦斯渗流速度表现出先减小后增大的趋势,在应力峰值处渗流速度出现突变点;随着加载速率的增加,瓦斯最小渗流速度V_(min)呈现出先减小后增大趋势,而瓦斯渗流速度变化量(V_(max)-V_(min))则先增加后减小;(2)随着加载应力的升高,瓦斯渗流温度呈线性增大趋势;瓦斯渗流温度变化差值(T_(max)-T_(min))随着加载速率的增大而逐渐减小;(3)加载速率较低时,约在煤样宏观破裂80%处渗流速度出现"平静期",而加载速度较高时,渗流温度在破裂前出现多次波动且有较长的"平静期",可作为突出煤失稳破坏的有效预警信息。

Combination response characteristics of gas seepage velocity-temperature under triaxial loading

Seepage velocity and temperature reflect the changes in the structure and energy of coal and can be used as early warning signals of coal and gas outburst.In this paper,the briquette was taken as the research object,and the self-developed test system was used to determine the joint response of seepage velocity and temperature under triaxial loading.The loading rate effect on gas seepage velocity and temperature was studied,and the relationship between gas seepage velocity and temperature and coal failure was established.The results show that:① During loading process,gas seepage velocity decreases first and then increases,and it changes suddenly at the peak of stress.With loading rate increases,the Vmin decreases first and then increases,while (Vmax-Vmin) increases first and then decreases.② With stress increases,gas temperature increases linearly,and the (Tmax-Tmin)decreases.③ When the loading rate is low,the seepage velocity appears “quiet period” at 80% of coal rupture.When the loading rate is high,the seepage temperature fluctuates many times before rupture and there is a longer “quiet period”.Those can be used as effective early warning information to highlight the coal rupture.