Experimental investigation of the seepage characteristics of a single fracture in limestone with different roughness and seepage fluids

To investigate the effects of roughness and seepage fluids on the seepage characteristics of limestone with rough fractures, five sets of limestone fracture specimens are obtained using 3D scanning and sculpting techniques, in which each set has the same fracture surface morphology. Both distilled water and sodium sulfate solutions were employed to implement seepage dissolution tests on the five sets of limestone specimens with different joint roughness coefficients (JRC). A novel method for characterizing the fracture surface morphology has been proposed, and the seepage characteristics of individual fractures have been investigated. Also, we analyzed the effects of different JRC and seepage solutions on the seepage parameters including seepage flow, equivalent hydraulic aperture, and permeability. Moreover, we presented a quantitative relationship between JRC and permeability. The results reveal that the seepage flow, equivalent hydraulic aperture, and permeability of each rough specimen under different seepage fluids decrease rapidly in the early stages and stabilize later. The dissolution can enhance the erosion of surface particles in the fracture and promote the seepage flow. The permeability and JRC follow a quadratic function in which the empirical parameters can be expressed as a quadratic function and an exponential function of time. This study can provide a theoretical basis for estimating the permeability of fracture with different roughness under different water environments.