承压富水煤层顶底板渗流特性及孔隙结构研究

Research on Seepage Characteristics and Pore Structure of Roof and Floor of Pressurized Rich Water Coal Seams

在山西邓家庄煤矿建设和开采过程中,发现了煤层作为承压裂隙含水层的特殊水文地质现象。为进一步探讨渗透力学性质在承压裂隙含水层中发挥的关键作用,取顶底板岩层岩样进行了岩石全应力-应变渗透试验和孔隙发育结构试验。结果表明,该煤矿煤层为承压裂隙型含水层,煤层裂隙承压水与顶底板总应力-应变渗透率及孔隙结构发育特征密切相关;离煤层越近,地层的水密性和塑性就越强,变形过程中地层的抗破坏能力也就越强,形成宏观导水裂隙的应变就越大;对于未发育裂隙,距离煤层30m以内的顶底板地层有效孔隙度小于2%,特别是距离煤层20 m以内的地层有效孔隙度小于1%,说明该地层具有较好的抗水性。

During the construction and mining process of Dengjiazhuang coal mine in Shanxi,a special hydrogeological phenomenon of coal seams as confined fracture aquifers was discovered.In order to further explore the key role of permeability mechanical properties in confined fractured aquifers,rock samples from the top and bottom layers were taken for complete stress-strain permeability tests and pore development structure tests.The results show that the coal seam in the coal mine is a pressurized fractured aquifer,and the pressurized water in the coal seam fractures is closely related to the total stress-strain permeability and pore structure development characteristics of the roof and floor.The closer to the coal seam,the stronger the water tightness and plasticity of the formation,and the stronger the resistance to failure of the formation during deformation,resulting in greater strain in the formation of macroscopic water conducting fractures.For undeveloped fractures,the effective porosity of the top and bottom strata within 30 meters of the coal seam is less than 2%,especially the effective porosity of the strata within 20 meters of the coal seam is less than 1%,indicating that the strata have good water resistance.