Several key issues in three-dimensional numerical analysis of slopes reinforced with anti-slide piles are systematically studied. A large finite element program considering the interaction of pile-soil-slope is used to achieve the factor of safety (FOS) and the critical slip surface (CSS) for the slopes stabilized by a row of piles

some key factors such as computational model scale

pile location

ratio of pile spacing to pile diameter

pile length and contact mode at the pile bottom are adequately discussed combined with a typical slope example. In addition

bending moments

shear force

horizontal displacement and lateral earth pressure for the stabilizing piles under four pile top constraints are also analyzed in detail. Some important conclusions are drawn according to the research results to guide the engineering practice and amend the design code for stabilizing piles

which include: (1) The FOS for a slope with reinforcing piles is the same under five computation model scales such as half pile

single pile

double of half piles

double piles

single pile and double of half piles. However

the computational cost under half pile condition is the least one. (2) The maximum FOS can be obtained when the piles are inserted in the middle of the slope

rather than the top or the toe of the slope. The relation between the FOS and pile location in a slope shows a parabolic curve. (3) The FOS for a slope with reinforcing piles will decrease with the increasing the ratio of pile spacing to pile diameter

the optimal ratio is S/D =2-6

because soil arching is formed between the piles. (4) The optimum stabilizing depth for the pile in homogeneous soils can be chosen to be 2/5 pile length.