Abstract: Rainfall is the most important cause of slope failure. The variation in stress state of soils due to rise of groundwater level and seepage of groundwater is critical to the deformation and failure of slopes during and after heavy rainfall. The stability of fill slope depends not only on the strength of fill material but also the drainage condition of the slope. Proper drainage control can not only limit the height of groundwater level, but also dissipate the build-up of excess pore pressure caused by shearing-induced contraction of soil. The possibility of liquefaction and flow failure of fill slope can be reduced consequently. The performance of compacted fill slope during rise of groundwater level is investigated by using a fully coupled procedure and the state-dependent dilatancy sand model. The interaction between pore water and soil skeleton including both buoyancy and seepage effects can be precisely taken into account in a fully coupled effective stress approach. The influence of the drainage condition of compacted fill on the stability of slope is examined. The analytical result indicates that the drainage condition in a compacted fill slope plays an important role in controlling the deformation of slope during and after heavy rainfall. Proper drainage control must be provided in remediation of loose fill slopes.

Key words: fully coupled, liquefaction, rainfall, slope