NUMERICAL ANALYSIS OF THE STABILITY OF A SLOPE REINFORCED WITH PILES

FEI CAI and KEIZO UGAI

ABSTRACT The effects of stabilizing piles on the stability of a slope are predicted by the three-dimensional elast-plastic shear strength reduction finite element method. The soil-pile interaction is simulated with zero-thickness elasto-plastic interface elements. The numerical results are compared with those obtained by Bishop's simplified method, where the reaction force of the piles is determined by Ito-Matsui's equation. The effects of the pile spacing, pile head condition  and  bending stiffness, and pile positions on the safety factor are analyzed. The shear strength reduction finite element method shows that the pile head conditions and bending stiffness can considerably influence the stability of the slop, but this cannot be indicated by the limit equilibrium method. The positions of the pile row have significant influence on the stability of the slope. The shear strength reduction finite element method indicates that the pile row needs to installed in the middle of the slope for maximum safety. By contrast. Bishop's simplified method shows that the pi should be installed slightly closer to the top of the slope.

Key words: finite element method, interface element, limit equilibrium method, pile, slope stability, three-dimension (IGC:E6)