Analysis of the migration characteristics of tracers in a heterogeneous flow field through a natural fracture of a domestic granite

Tracers migration experiment was performed in a natural fracture of a domestic granite. The scale of rock fracture was 100x60x40(cm). In order to observe the migration characteristics, two kinds of nonsorbing tracers were used; as high molecular organic dyes, Eosine, and NaLS, and as anions, Bromide and Chloride. Tracers was injected in a borehole as a band funtion and collected at the opposite borehole. A variable aperture channel model with particle tracking method was used to characterize the aperture width of the fracture and to simulate solute transport. The heterogeneous flow field was modeled by a variable aperture channel model after characterizing aperture distribution by hydraulic tests through boreholes. The particle tracking method applied effectively in simulating tracers transport through a heterogeneous flow field in the rock fracture. Simulated results show that tracers do not migrate through the shortest straight line between inlet and outlet, but migrate through the paths having lowest flow resistance. that is channeling flow