加卸载应力条件下原煤力学与渗透特性的实验研究
Experimental Study of Mechanical and Permeability Characteristics of Raw CoalUnder Loading-unloading Stress Conditions
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摘要: 以川煤集团芙蓉公司某煤矿C1煤层的煤样为研究对象,利用煤岩热流固耦合三轴伺服渗流实验装置(THM-2),进行加卸载应力条件下原煤力学及渗透特性实验。研究结果表明:同一加卸载控制点下,原煤破坏时的体应变随加卸载速率比的增大而减小,破坏时的径向应变和轴向应变随加卸载速率比的增大而增大,随加卸载速率比增大,原煤破坏形态逐渐由多宏观断裂面向单一宏观断裂面发展。同一加卸载速率比下,原煤强度随加卸载控制点的增大而增大,原煤的破坏角随加卸载控制点的增大而减小。原煤在加卸载应力条件下,随着加卸载速率比增大,屈服阶段的渗透率响应变化量呈线性关系降低,加卸载控制点到原煤产生渗透率变化的应变响应变化量呈线性关系增大。Abstract: Taking the natural coal drilled from C1 coal bed of a coal mine of Sichuan Coal Group Furong Company as research object, we investigated the mechanical and permeability characteristics of raw coal under different loading-unloading stress conditions based on the triaxial servo-controlled seepage equipment for thermal-hydrological-mechanical coupling of coal and rock(THM-2). The results showed that: under the same loading-unloading control point, with the increasement of loading-unloading rate ratio, the volumetric strain decreased, but the axial strain and the radial strain increased, the failure pattern of coal gradually developed from several macroscopic fracture to single macroscopic fracture. Under the same loading-unloading rate ratio, with the increasement of loading-unloading control point, the intensity of coal increased, but the failure angle of coal decreased. During the yield stage, with the increase of loading-unloading rate ratio, the response variation of permeability decreased with a linear relationship. However, the response variation of strain from loading-unloading control point to permeability transformation point increased with a linear relationship.