不排气条件下低渗透岩石力学特性试验

Experimental study on mechanical characteristics of low permeability rock under gas undrained condition

以低渗透致密红砂岩为研究对象,开展了不同围压和孔隙气压下的常规三轴不排气试验,分析了不同应力路径下,围压与孔隙气压对岩石力学特性的影响。试验结果表明:围压对砂岩具有强化作用;随着围压增大,抗压强度与延性明显增大,多呈现剪切破坏形式;孔隙气压使砂岩的抗压强度降低,脆性提高,砂岩内部张力增大,对砂岩内部连续结构产生破坏,易产生劈裂破坏面。

To analyze the influence of confining pressure and pore air pressure on the rock mechanical properties under different stress paths,conventional triaxial tests under the gas undrained condition were carried out on a low-permeability and tight red sandstone.The experimental results show that the confining pressure has a strengthening effect on the sandstone.As the confining pressure increases,the strength and ductility of the rock increase significantly,and the rocks eventually show the form of shear failure.The pore air pressure reduces the compressive strength,while increasing the brittleness and internal tension of the sandstone,by damaging the internal continuous structure and leading to the occurrence of splitting failure plane.