Experimental and Theoretical Study of Seepage Models under Confining Pressure for a Single Rock Fracture

The engineering water inrush events were affected by the hydraulic characteristics of the fractures. In order to quantitatively study the seepage characteristics of the fractures, the experimental analysis of artificial fracture of shale was carried out under different confining pressure (22 MPa-38 MPa) to explore the influence of confining pressure on seepage characteristics. Three theoretical constitutive formulas to describe the characteristics of seepage were proposed based on cubic law and fracture constitutive equation (Bandis model, Rong model, Sun model), and these theoretical constitutive formulas all had good fitting results to experiment results which indicated that the derived formulas are feasible. The parameters for the three models were compared, among which the Rong model was more suitable to describe the connection between (Q) and (Pc). Rong model and Sun model were highly descriptive to the relationship between (Pc) and (Ps). The formulas that based on three theoretical models can provide quantitative calculation for the influence of in-situ stress change on the seepage of fractures in engineering practice.