不同层理方向对原煤变形及渗流特性的影响

Effect of different bedding directions on coal deformation and permeability characteristics

利用自行研制的含瓦斯煤热流固耦合伺服渗流试验装置,以平行和垂直层理2种不同的原煤试样为研究对象,进行相同有效应力、瓦斯压力条件下,不同轴压、围压组合;相同瓦斯压力、静水压力条件下,不同有效应力的渗流试验,探究其变形及渗透率的差异。研究结果表明:平行层理试样沿z方向的裂隙度φz大于垂直层理试样,垂直层理试样的总裂隙度φ大于平行层理试样;煤体中平行层理方向的裂隙度大于垂直层理方向;在静水压力下,平行层理试样渗透率大于垂直层理试样,煤体平行层理方向渗透性高于垂直层理方向;基于平板流体理论,得出了渗透率与径向应变呈二次函数关系,在煤体中平行层理方向的初始裂隙度系数β是垂直层理方向的1.5~2.0倍;当考虑渗流通道为贯通裂隙时,平行层理方向的初始裂隙度φ0与初始裂隙开度平方d20的乘积是垂直层理方向的1.5~2.0倍。

A self-developed device called the gas-bearing coal heat solid coupling servo seepage device was used to conduct the percolation test of two different coal samples( parallel bedding coal and perpendicular bedding coal) under different condition settings to study the differences of deformation and permeability between these two types of coal samples. In the first section of the percolation test,the effective stress and gas pressure remained the same,while the axial pressure and confining pressure were different. In the second section,the gas pressure and hydrostatic pressure remained the same,while the effective stress was different. The result shows that the degree of fracture along the direction of z of parallel bedding sample is bigger than that of vertical bedding sample. The total degree of vertical stratification fractured specimen 'φ'is bigger than the parallel bedding sample. In coal,the total fracture of vertical bedding direction is bigger than that of parallel bedding direction. The degree of fracture of parallel bedding sample is bigger than that of vertical bedding sample. Under hydrostatic pressure,the degree of fracture of parallel bedding direction isbigger than that of vertical bedding direction. According to the theory of tablet fluid,quadric relationship between permeability and radial strain can be obtained. The initial crack coefficient of parallel bedding sample is 1. 5- 2. 0 times bigger than that of vertical bedding sample in coal. When the flow channel is considered as transfixion crack,the product of the initial crack coefficient and the square of the initial fracture aperture of parallel bedding sample is 1. 5- 2. 0times bigger than that of vertical bedding sample.