Creep behavior and permeability evolution of coal pillar dam for underground water reservoir

Using goof as water storage space plays a vital role in the ecological environment and economic development of arid mining areas, while the rock strength and the stability of coal pillars in underground water reservoirs are closely related to creep process. In this work, triaxial creep-seepage tests were conducted for coal samples to develop new insights into the creep behavior and permeability evolution. The results showed that the creep deformation and permeability evolution of coal samples exhibit three stages, namely, the compaction hardening stage before the stress threshold, volumetric compaction stage, and volumetric dilatancy stage. The coal permeability decreases first and then increases with the creep strain and it is well correlated with the variation of volumetric strain.