The application of unsaturated soil mechanics to the assessment of weather-related geo-hazards

The primary goal of this paper is to illustrate the manner whereby unsaturated soil mechanics can be taken from the soil property assessment level using techniques based on the soil-water characteristic curve, (SWCC), to the quantification of geo-hazards. A concise description of a weather-related geo-hazards assessment model (W-GHA model) is presented. The soil system is represented by a series of partial differential equations (PDE's) governing conservation of mass and momentum and an equation for the soil-atmosphere coupling. Slope stability conditions are quantified using a "dynamic programming" solution. Parameter uncertainty is addressed through a probabilistic and sensitivity analysis framework. An example problem is presented. It is shown that the probability of failure and factor of safety provide important, complementary information. The sensitivity of the input parameters is presented and discussed. Some soil properties are found to have time-dependent sensitivity. Several input parameters appear to have negligible sensitivity and should not be considered random variables under the soil and atmospheric conditions presented herein.