THE EFFECTS OF FLUID’S PHYSICOCHEMICAL CHARACTERISTICS ON PIPING EROSION PROGRESSION OF A SILTY SAND

Open Access
Author:
Ma, Yuetan
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 28, 2018
Committee Members:
  • Ming Xiao, Thesis Advisor
Keywords:
  • Piping erosion
  • Viscosity
  • pH
  • Ionic strength
  • Hole erosion test
  • Erosion rate index
  • Physicochemical effect
Abstract:
This thesis presents an experimental research for studying the absolute and interactive effects of three physicochemical characteristics of permeating fluids (viscosity, pH, and ionic strength) on piping erosion progression 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 silty clayey sand specimens. Erosion rate index, an important index was used to quantify the relative erosive capacity of the test fluids. 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 statistic model to describe the effects of the three factors and their interactions. The main findings include: (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 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.