Hydraulic Characteristics Of Fracture With Fractal Surface

It is hard to quantify the roughness of rock fractures with commonly used function because rock fracture surfaces are rough. If the flow characteristics of the fractures are needed to be accurately analyzed, the roughness and the curvature of fractures are also required to be simulated. The accurate expression of the rough surface can make a great influence on numerical simulation of seepage field of rock fracture. The development of fractal theory made a great contribution to the research of roughness of rock fracture surface, and opened up new field for the study of hydraulic characteristics of fracture. A lot of studies show that the binary fractal interpolation is used in the study of roughness of rock fracture surface based on the statistical self-similarity of rock fracture surface.Making use of the method of the self-affine fractal interpolation, the rock fracture surfaces are generated in computer. Lots of data points from rock fracture surface are obtained. Numerical models can be constructed with these data points. The fractal dimension of the numerical models will increase with the increasing of roughness of fracture surface. The water flow problem in fractal rock fracture is simulated. The equivalent transmissibility of rough fracture surface with different fractal dimension can be calculated by numerical calculation. The relationship between fractal dimension of rough surface and equivalent transmissibility can be obtained. And flow characteristics in fractal fracture also can be solved through digital simulation and image display in computer.The numerical results show that the fractal dimension of the rough surface will increase with the rising rock wall roughness. While the pressure difference between the inlet of fracture and the outlet of fracture is constant, the transmissibility of fracture surface will decrease with the rising fractal dimension. And while the fractal dimension of the rough surface of fracture is constant and the pressure difference is changed, the average velocity of a cross section will increase with the rising pressure difference, the transmissibility will decrease with the rising pressure difference.