蠕变对含瓦斯煤渗透率影响的试验分析

EXPERIMENTAL ANALYSIS OF INFLUENCE OF CREEP ON PERMEABILITY OF GAS-BERING COAL

以重庆市松藻煤电公司石壕矿原煤制备的型煤试样为研究对象,设计含瓦斯试样的三轴蠕变及渗流试验方法和步骤。利用试样瓦斯渗透仪试验装置,在不同温度条件及不同有效应力水平下,对型煤试样进行三轴蠕变及渗透性试验,获得大量蠕变前后不同有效应力和不同温度条件下的渗流试验数据,研究蠕变对试样渗透率的影响规律。研究结果表明:在相同温度与有效应力条件下,蠕变后试样渗透率降低,下降幅度为25.2%～38.7%;在三轴应力条件下,随着有效应力增大和温度升高,蠕变前后试样渗透率逐渐降低,探讨两因素对渗透率的影响机制;定义渗透率损伤率来表示蠕变使得试样渗透率减小的程度,当温度一定时,渗透率损伤率与有效应力符合线性关系,该渗透率损伤率随有效应力增加而增加,且温度越高,增加的速率越大;在不同温度及有效应力耦合作用下,蠕变对渗透率的影响程度不同。研究结果对进一步认识瓦斯运移规律具有一定的意义。

Taking briquette made from raw coal as an object of study, which is from Shihao mine of Songzao Gas and Electric Company in Chongqing, the method and steps of triaxial test of creep and seepage for coal specimens containing gas are designed. By means of experimental equipments of coal seepage, under different temperatures and effective stress situations, the seepage test before and after coal creep are performed and a large number of test data are obtained; the effect law of creep on coal permeability is investigated based on the experimental results. The results show that, with the same temperature and average effective stress, permeability decreases 38.7% to 25.2% after the creep of coal sample; under the triaxial stresses condition, the higher the temperature and the greater the average effective stress are, the lower the coal gas permeability tends to be; meanwhile, the mechanism of their effects of the two factors on permeability has been discussed; the permeability loss caused by creep can not be partly recoveried; with a certain temperature, the permeability of damage and effective stresses conforms to the linear relationship; the permeability of damage increases with an increase in effective stress, and the higher the temperature is, the greater the rate of increase tends to be; with different temperatures and effective stress coupling, the influence of creep on coal permeability is different. The results have a reference value for further exploring the law of gas seepage in coal.