Vertical Capillary Barriers and Wick Drains to Mitigate the Rain-induced Slope Failures: Numerical Analysis

Abstract

Slope failures are catastrophic when they suddenly occur in human habitats. The stability of slopes gradually diminishes with heavy rainfall due to the increase in pore water pressure; subsequently, the shear strength of the slope soil decreases. The effect of rainwater on the instability of slopes was studied in this research with respect to factor of safety values. Accordingly, finite element analysis and limit equilibrium analysis were conducted using a 2D model of a soil slope in SEEP/W and SLOPE/W programs to observe the responses of the slope soil profile under heavy rainfall. Movement of the wetting front and the fluctuation of the groundwater table were studied to develop a drainage mechanism, thereby to control the effect of infiltrated rainwater on slope failure. A conceptual method was introduced in this study by developing a numerical model with an effective drainage system which consists of vertical capillary barriers with combination of horizontal wick drains in a cascade manner in the slope. This method exhibited high stability of the slopes even with continuous rainfall for number of days, therefore, applicable as a sustainable prevention method of slope failures.