Experimental investigation of seepage characteristics in porous rocks with a single fracture

Abstract

An experimental investigation of seepage characteristics in porous rocks with a single fracture is presented. A seepage system was developed and assembled in the laboratory using two experimental setups. Tests were conducted to quantify the effects of influent pattern, fracture aperture (B), coefficient of permeability of the porous medium (k), hydraulic gradient (J), and water temperature (T) on the seepage characteristics of a porous concrete matrix with a fracture; the porous concrete, with controlled characteristics, was designed to simulate porous rock. The mechanisms of seepage exchange between the porous media and the fracture are discussed, and a new formula for describing the seepage mechanism in a porous rock with a single fracture is proposed. The results showed that B, k, and influent pattern had significant effects on the seepage between the fracture and the porous concrete. The amount of effluent exiting the fracture was greater than that exiting the porous concrete blocks. The proposed model indicated that when B was less than 3.0 mm, the variation in fracture aperture had a significant influence on the effluent from the fracture, while its influence was relatively small when B was greater than 3.0 mm. When k was less than 1.0 cm/s and B increased to 4.8 mm, seepage exited only via the fracture. The proposed mathematical model can be used to effectively estimate the seepage through porous rocks with a fracture.