ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉Little attention has been paid to non-Darcy fluid flow through rough-walled rock joints under high hydraulic gradient. Water fluid flow through splitting granite joints was tested beyond the range of previously tested conditions by using an experimental apparatus designed for this study. This apparatus facilitated the quantification of the effects of joint surface roughness and aperture on fluid flow properties. Experimental results showed that Forchheimer’s law could provide an excellent description of the nonlinear relationship between hydraulic gradient and flow velocity, and the variations of Forchheimer coefficients with joint surface roughness and aperture were further explored. In this work, the Reynolds numbers varied between 2,881 and 290,338, and greatly exceeded the critical value of 2,300. Moreover, the fluid flow entered the turbulent flow regime. In accordance with the discriminant factor 〈em〉α〈/em〉 = 0.9 on the basis of Forchheimer’s law, the fluid flow regimes were further divided into two categories: weak turbulence and fully developed turbulence. The corresponding critical Reynolds numbers were obtained and ranged from 17,169 to 94,385. Finally, a new seepage calculation formula for fluid flow through open rough-walled rock joints was established and verified by experimental observations and other formulae. Through a comprehensive consideration of the joint surface roughness and the uneven aperture distribution, the proposed formula could reflect the real fluid flow situation. The findings may prove beneficial for improving understanding of the nonlinear fluid flow in jointed rocks.〈/p〉