不同温度应力条件下煤体渗透率实验研究

Experiment Study of Coal Permeability Under Different Temperature and Stress

为了深入研究渗透率与温度和应力的关系,分别采用吸附性气体甲烷和非吸附气体氦气,进行了不同应力条件,不同温度条件下的煤体渗流实验.结果表明,不同有效应力条件下煤体渗透率与温度的关系,并非单调递增或单调递减,而是存在一个转折区,转折区的位置取决于有效应力与热应力的大小对比关系,低有效应力条件下,热应力大于有效应力,煤体外膨胀,渗透率随温度的升高而增大,呈正指数关系;高有效应力条件下,热应力小于有效应力,煤体内膨胀,渗透率随温度的增加而减小,呈负指数关系.这一发现将以往的矛盾结果统一了起来.

The relationship between coal permeability and the temperature or stress of the sample was determined by CH4 or He permeability measurements made under different temperatures and stresses. The results show that the relationship between coal permeability and temperature under different effective stress is not always a monotonically increasing or decreasing function. There is an inflection in permeability when the temperature increases. Under low effective stress the stress from thermal expansion is larger than the applied effective stress. Then the coal expands outside and the permeability increases as the temperature increases, showing a positive exponential relationship. Under high effective stress thermal stress is smaller than the effective stress and the coal expands inside. Then the permeability decreases as the temperature increases in a negative exponential relationship. These discoveries explain past, conflicting results.