Experimental investigation of contaminant migration in filled fracture

Experiment equipments involved in the single tube fracture and double tube fracture models are designed to research the characteristics of groundwater flow and solute transport in filled fracture. During the experiment, the state of groundwater flow can be characterized as linear flow, and satisfies Darcy’s law. Therefore, based on the pipe flow of hydraulics and Darcy’s law, the flow rate and water flow velocity can be calculated. Also, dispersion parameters were calculated with the fitting of observed data and analytical solution in the single tube fracture model. Furthermore, effects of some factors on solute transport are involved in the double tube fracture model, and length of branch fracture, particles’ diameter and flow rate in water inlet have been discussed. Results show that the arrival time of concentration peak value in the single tube fracture model is faster than that in the double tube fracture model, and two concentration peak values exist in the double tube fracture model. Arrival time of concentration peak value is faster with the increase of branch fracture length. Furthermore, if the branch fracture is longer, arrival time of the first concentration peak value is faster, while arrival time of the second concentration peak value is slower, relative to short branch fracture.