Experimental Study Of Water Flow And Solute Transport In A Single Fracture

In recent years, groundwater pollution has caused serious ecological crisis to our country and becames one of the major confinement factors affected on sustainable development of our society and economy. The paper is sponsored by National Natural Science fundation: Experimental study of groundwater movement and solute transport in bedrock fracture media(40202027) and Huo Yingdong Educational fundation: Experimental study of contaminant's non-Fickian transport mechanism in bedrock fracture media(91079). Mechanism of fracture water movement and contaminant transport in a single fracture was studied in the paper. It's result has significant theory and practice value.In this paper, Studies on water flow and solute transport in single fracture were summarized. Under the condition of water flow behavior is turbulent flow, The relation among average flow velocity, Reynolds number and hydraulic gradient in single fracture(fracture aperture: 4mm~9mm) is analyzed according to indoor simulation experiment. On the base of these works, chrematistics of solute transport in a single fracture are studied. Both conventional convection-dispersion model and neural network model are used to model solute transport in single fracture.Through above analysis of experiment, statistical study and model verification, conclusions are drawn as folio wings:(1) Under the condition of this paper's experiment, Darcy law can't applied and water flow equation of motion in a single fracture is nonlinear equation. When flow quantity and other conditions don't change, fracture aperture has prodigious affect on Reynolds number;(2) When water flow behavior is turbulent flow, solute transport appears back mixing and non-Fickian transport phenomenon. Conventional convection- dispersion equation can't explain solute's non-Fickian transport phenomenon;(3) Results from the used neural network model show that neural network model can simulates solute transport in a single fracture well. The model's accuracy is high, can reflect primary rule of solute transport accurately.