Seismic stability of slopes reinforced with sleeved and unsleeved piles

The development of urban areas in hilly portions of the ground has caused the construction of high rise structures on slopes which sometimes are in a marginal stability. In order to decrease the lateral loads transferred from piles to slopes especially at shallow depths, it is suggested to use of compressible materials such as polystyrene or geofoam as an annulus or sleeve located all-round the outer periphery of concrete piles. The dynamic soil-sleeved pile interaction has not been reported in the literature before. In this paper, 3D finite-difference dynamic analyses using an elastoplastic constitutive model considering dynamic properties of the soil are carried out to study the dynamic soil-pile interaction for both sleeved and unsleeved piles constructed in sloping ground. The effects of sleeve part on stability results, various lengths of piles, various slopes of the ground, various spaces between piles and effects of single or group of piles are investigated. The stability of slopes has been evaluated using a new code based on Strength Reduction Method technique. The variations of shear force and bending moment of piles during dynamic loading have been studied too. Finally, the effective arching distance between piles would be discussed.