The Mechanism And Simulating Study Of Water Movement And Solute Transport In A Single Gradient Fracture

The paper is sponsored by National Natural Science Foundation of China: "Experimental study of groundwater movement and solute transport in bedrock fracture media"(40202027) and "Huo Yingdong Educational Foundation: Experimental study of contaminant's non-Fickian transport mechanism in bedrock fracture media"(91079). The effect of fracture inclination to mechanism of fracture water movement and solute transport in a single fracture is studied in the paper. The results have significant theory and practice value.In this paper, studies on water movement and solute transport in a single fracture are reviewed and summarized. Based on simulating experiment in laboratory, the relationship among the average velocity of fiow(v),hydraulic gradient (i) and fracture inclination (θ) of a single fracture under confined condition is analyzed. And then the inclination between single fracture and horizontal level is changed to investigate howθaffects water movement and solute transport in a single fracture. By experiment analyzing, statistic investigating and model improving, some significant conclusions are summarized.Experiment results indicate that: (1) Water flow in single parallel fracture with different fracture inclinations under the hydraulic condition of the text is laminar flow. The relation between v and i obeys Darcy law. (2) Asθincreases, slope of linearity relation between v and i decreases, and the change seems to obey some rule. Therefore, a model with v,i,θas its variables is upbuilt, and its relativity is good. (3)θaffects solute transport in a single fracture, and it shows that: asθincreases, both longitudinal dispersion coefficient (D_L ) and transverse dispersion coefficient D_T) increase. (4) Relationship between D_L and distance of solute transport(L) is different with solute transport model under the condition of one dimension field,one dimension dispersion. According to hydraulic condition of the text, a model which considersθas an effect factor to solute transport is upbuilt. The model can describe solute transport under the condition of one dimension field,two dimension dispersion better. (5) Pictures of pollute plume shows:θincreases with D_T of solute transport. This conclusion accords with the calculation result of experiment data.