Probabilistic Analysis of Unsaturated Fly Ash Slope

Abstract

To prevent fly ash from becoming an environmental hazard, it is very often used as a fill material in the construction of embankments. The stability of slopes incorporating the unsaturated behavior is of primary concern in these structures. This necessitates estimating the water retention characteristic curve (WRCC) of fly ash. However, the literature notes various uncertainties associated with the measurement of WRCC, mostly attributed to the inadequacy of instruments to measure wide range of suction. This paper investigates the impact of measurement uncertainties in WRCC on the reliability analysis of fly ash slope. The study shows a significant impact of uncertainties in WRCC on determining slope reliability. To quantify these uncertainties, a probabilistic model for WRCC is developed using the Gaussian copula and is incorporated into an unsaturated slope stability framework using Monte Carlo simulation. The study also shows the impact of the degree of correlation among WRCC parameters on the reliability analysis of slopes.