Flow Characteristics of Deep Fractured Rock Mass under Water-Rock Mass Coupling

Abstract

The deeply fractured rock mass exists in the environment of in-situ stress and high seepage pressure, and they are prone to seepage-slipping failure. Therefore, it is of excellent engineering value and theoretical significance to study the nonlinear seepage evolution of fractured rock mass under water-rock mass coupling. This paper taking the persistent fracture granite as a tested sample, a series of seepage tests of persistent fracture granite under different seepage pressures were carried out. The nonlinear seepage evolution of fractured granite with different JRC values under water-rock mass coupling was studied, and the 3D reconstruction of the fracture surface was carried out after the experiment. The influence of the roughness degree of fracture surface on the permeability of fractured rock mass is investigated. Based on the experimental results, the non-darcy flow behavior of the fractured granite is analyzed by using the quadratic function-type Forchheimer formula. The results show that the permeability of the fractured granite increases nonlinearly with the increase of seepage gradient when the volume flow rate over 20mm3/s; The research results are of great significance for the study of nonlinear seepage evolution of rock mass with different JRC values under high in-situ stress and high seepage pressure.