Experimental Study On Mechanism Of Water Flow And Solute Transport In Intersectional Fracture

With the development of the society, various underground projects (included water conservancy, mining projects and geological disposal projects of nuclear wastes, etc) became more and more, which their scales became larger. The study on the groundwater also became more important in many countries. The groundwater flow and solute transport is very complex because of the intense variability in rock network fracture. How to simulate the water flow and solute transport is a very important question. The paper is sponsored by National Natural Science Foundation and Huo Yingdong Educational Foundation. On the basis of the studies about water flow and solute transport in the fractured media at home and abroad, this paper studies and analyses water flow and solute transport in the intersection fractures. A set of experiment equipment simulating groundwater flow and solute transport is designed. The test simulating groundwater flow and solute transport in the intersection fracture is performed. The relationship between the breakthrough and the velocity and fracture width is researched. The conclusions are as follows:(1)Under the condition of this paper's experiment(fracture width: 2mm~8mm, velocity: 0.9563cm/s~6.6575cm/s, Reynolds(Re): 8.2963-210.1923), the velocity and the hydraulic gradient of the water flow at the intersection point is researched, the traditional Darcy Law can applied. Both the research on Reynolds and the dyeing tracer test indicate that the flow keeps laminar after passing the intersection point. The traditional LCL (local cubic law) is tested. It has difficulty in characterizing water flow in intersected fracture.(2)The method which characterizes the water flow distribution in intersection point is improved on. Experimental data analysis indicates that the new method is more concise than the old one. It is applicable to the water flow distributive mechanism in the intersection point under this paper's experiment condition. Based on the research, the mechanism of the water flow distributions affected by the fracture width and velocity in intersection point is gained.(3)Because of the affection of the circumfluence in the intersection point, solute transport appears non-Fickian transport phenomenon. Conventional convection-dispersion equation can't explain solute non-Fickian transport phenomenon. The breakthrough curve of non-Fickian transport under Darcy flow is drawn.