| Popis: |
This article presents an experimental study of the relative and interactive effects of three physicochemical characteristics of permeating fluids (viscosity, pH, and ionic strength) on piping erosion of a sandy soil under turbulent flow. Full-factorial experimental design was used to produce eight types of fluids of various combinations of the three fluid characteristics. Hole erosion tests were conducted on identically prepared sandy specimens. The erosion rate index was used to evaluate the effects of fluid properties on piping. The erosion rate index was quantified for two repeat trials for each of the eight test fluids. Regression analysis was conducted on the results to generate a statistical model to describe the relative effects of the three factors and their interactions. The main findings include the following: (1) Viscosity, pH, and ionic strength were all determined to be significant factors on the rate of erosion. The two-way interactions between viscosity and pH and between viscosity and ionic strength were also determined to be significant interaction factors, while the interaction between pH and ionic strength did not prove to be statistically significant. (2) Higher pH of the test fluid causes higher erosive capacity; higher ionic strength causes lower erosive capacity of fluid. (3) At low viscosity, ionic strength does not affect the erosion, but when the viscosity is higher (or the fluid temperature is colder), higher ionic strength causes much less erosion. There is almost no interactive effect between pH and ionic strength. |
