Stability of Subgrade Slope along River Subjected to Water Level Fluctuations and Stream Erosion

Abstract

Water level fluctuation, water pressure in tension crack and stream erosion are the important factors for failure of subgrade slope along the river. Based on the limit equilibrium theory, the dimensionless expressions of safety factor for subgrade slope stability along river subjected to the condition of many factors were deduced. And a rounded analysis for the subgrade slope was performed, in which the water level in river, water pressure in tension crack and stream erosion are major factors. Parametric analysis shows that (1) Rapid drawdown of water level, water level elevation in tension crack, seepage force in failure face, blocked outflow slot, and stream erosion in toe of subgrade slope has a disadvantage effect on the subgrade slope stability. 2) The subgrade slope stability factor decreases first and increases afterward with the increasing water level in river. High water–level in river has an advantageous effect on the subgrade slope stability, while low water—level in river is an adverse factor for the subgrade slope stability. Theoretically, these analysis results gave an answer to the problem why some subgrade slopes along river in mountain areas can not maintain their stability in rainy season.