低应力下原煤各向异性渗透特特性试验研究
Experimental study on anisotropic permeability of raw coal under low stress
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摘要: 为了探究低应力下原煤的各向异性渗透特性,以漳村煤矿、亭南煤矿、新景煤矿煤样为研究对象,利用改进的三轴渗流试验装置,开展了沿同一试样面割理、端割理和垂直层理方向,恒围压轴压、变孔隙压力下的渗透试验。结果表明:在恒围压轴压下,通过煤样的流量随着渗透压差的增大而增大,在相同的渗透压差下,流量大小与渗流的方向紧密相关;在相同平均孔隙压力下,面割理方向渗透率略大于端割理方向而远大于垂直层理方向;低应力下面割理、端割理方向的渗透率相差不大,平行层理面内渗透率相近并非偶然,煤的渗透具有横观各向同性特征;煤体应力增大是导致端割理和面割理方向渗透率产生差异的主要原因。Abstract: In order to explore the anisotropic permeability of raw coal under low stress, taking the coal samples of Zhangcun Coal Mine, Tingnan Coal Mine and Xinjing Coal Mine as the research objects, using the improved triaxial seepage test device, the permeability tests under constant confining pressure and variable pore pressure along the direction of coal sample face cleat, butt cleat and vertical bedding were carried out. The results show that under the same confining pressure and axial pressure, the flow through the coal sample increases with the increase of osmotic pressure difference. Under the same osmotic pressure difference, the flow is closely related to the direction of seepage. The permeability in the face cleat direction is slightly larger than that in the butt cleat direction and much larger than that in the vertical bedding direction under the same average pore pressure. There is little difference in permeability between face cleat and butt cleat under low stress. It is not accident that the permeability in parallel bedding plane is similar, and the permeability of coal has the characteristics of transverse isotropy. The increase of coal stress is the main reason for the difference of permeability between butt cleat and face cleat.
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Keywords:
- low stress /
- permeability /
- anisotropy /
- cleat /
- bedding /
- pore pressure
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