Abstract -- The traditional analysis of slope stability has been carried out using unchanged values of soil and hydrological parameters. The time of slope failure is not obtained from such type of analysis. It is preferred to have an idea on the time when a slope would fail. Such information can be used for warning of potential slope stability problems. There, time-dependent slope stability problem is worthy of study.
Many slopes failed during or after heavy rainfalls. The mechanisms responsible for the slope failure, in this case, may include infiltration of water into subsurface. The infiltration results in an increase in unit weight of soil and a decrease in strength of soil. The objectives of this research program are to study the infiltration characteristics of rainfall on slopes, to determine properties of unsaturated soils obtained from test site, and to develop a methodology for analysis of time-dependent slope stability under rainfall conditions.
The model analysis of relation between rainfall infiltration and slope stability has been finished in this project, so that the factor of safety of a slope relating to the rainfall can be determined. Information on variation of soil water content related to amount of rainfall is obtained in field tests. According to the present data, this is no difference between a 10cm deep soil with 2 mm rainfall and 20 cm deep soil with 3 mm rainfall.