Abstract: Racked rock exists in a large number of practical projects,and the permeability of rock fracture changes with the size,However,there are many factors affecting the seepage size effect,and the control mechanism is not clear.In this experiment,radial flow is used as the research model to carry out seepage test on artificial single fracture,at the same time,using the visibility of polymethyl methacrylate,observe the fluid flow in the fracture,so as to further analyze the influence of different roughness on the permeability of single fracture.The results show that there is a size effect on the permeability of rock fractures in radial seepage of single fracture,the permeability increases with the increase of fracture size,and the greater the roughness,the slower the permeability increases with the size.

Key words: Size effect,Roughness,Visualization