煤岩吸附—解吸变形各向异性特征试验分析

Experimental study on anisotropic characteristics of coal deformation caused by gas adsorption and desorption

在井下瓦斯抽采和地面煤层气开发过程中,气体吸附和解吸会导致煤基质的膨胀和收缩变形。采用自主研发的煤岩气体吸附—解吸变形试验系统,对鹤壁六矿二_1煤层贫瘦煤煤样在不同气体压力下的吸附—解吸变形全过程进行了测试。试验结果表明:①煤样在吸附膨胀和解吸收缩变形过程中均呈现各向异性特征,垂直层理方向变形量最大,平行层理垂直面割理方向次之,平行层理垂直端割理方向最小;②煤岩吸附膨胀和解吸收缩变形量随气体压力的增加而增大,但平行层理垂直面割理方向与垂直端割理方向的变形值之比逐渐减小,各向异性程度逐渐减弱;③煤岩吸附膨胀变形是一个不可逆过程,煤岩吸附—解吸残余变形量与气体压力呈正线性相关性。

In the process of underground gas extraction and development of coalbed methane, the gas adsorption and desorption will cause coal matrix swelling and shrinkage. In order to better analyze the anisotropic characteristics of coal deformation caused by gas adsorption and desorption, we test meager lean coal samples from two-1 coal seam of Hebi No. 6 Coal Mine under different gas pressure with a self-developed coal deformation test system. The following phenomena are observed: A. Coal samples show anisotropic characteristics in the process of coal matrix swelling and shrinkage due to gas adsorption and desorption, the deformation in the vertical bedding direction is the largest, the direction in parallel bedding vertical face cleat is the second, and the direction in parallel bedding vertical butt cleat is the smallest;B. The deformation of coal matrix swelling and shrinkage increases with the increase of gas pressure, but the deformation ratio between parallel bedding vertical face cleat direction and vertical butt cleat direction decreases gradually, and their anisotropy diminish gradually;C. The deformation of coal matrix after swelling and shrinkage is an irreversible process, and the residual deformation of coal increases with the increase of gas pressure, and it has a linear correlation with the gas pressure.