Three-dimensional numerical modelling of discrete piles used to stabilize landslides

Three-dimensional finite difference analyses have been carried out to investigate the behaviour of a single pile used to stabilize a slipping mass of soil by embedment into a stable stratum. Analyses were initially carried out to determine the reduction in the limiting pile soil lateral force per metre length, p(u), close to the unconfined ground surface. The analyses then explore the failure mechanisms for landslide stabilizing piles categorized by Viggiani. The effects of varying the strength of the slip plane interface between the sliding and stable strata, and of a sloping ground surface on the behaviour of the pile are then investigated. The results from numerical models with a rigid pile, a distinct plane of sliding, and a horizontal ground surface, as assumed by Viggiani, agree well with his theoretical mechanisms. Lower values of p(u) close to the ground surface and adjacent to the sliding plane are found to reduce the maximum shear resistance that piles can provide to The slipping mass when compared with Viggiani's theoretical solutions. Further analyses show that the strength of the slip plane interface has a considerable influence on pile behaviour, and that the slope of the ground surface is only significant above a certain angle.