Three-dimensional finite element analysis for soil slopes stabilisation using piles

ABSTRACT

This paper presents the analytical methods of slope-stabilising piles using the three-dimensional (3-D) finite element (FE) analysis with the strength reduction method (SRM). This 3-D FE model is employed to overcome the limitations observed in two-dimensional (2-D) FE analysis. The solutions obtained from 3-D FE analyses are verified to be less conservative in this paper. The 3-D analysis is considered to be of particular importance to pile-slope problems. The soil that flows between piles cannot be taken account properly in the 2-D FE analysis. The method adopted in this paper can avoid the assumption of soil movement and the pressure distribution along the piles subjected to soil movement. The numerical analysis employs the Mohr–Coulomb failure criterion with the strength reduction technique for soil and an elastic member for piles. The spacing effect of the pile is considered in the 3-D model, the S/D (S: centre to centre, D: diameter of pile) ratio, equal to 4.0, is found to be equivalent to the single pile stabilisation. The middle portion of the slope is identified as the optimal location to place the piles. The proper length of the pile, which can be used to stabilise the slope, is also examined using 3-D FE analyses. It is concluded that L/H greater or equal 0.70 is recommended (L: pile length, H: slope height). The numerical analyses are conducted based on a coupled analysis, which simultaneously considers both the slope stability and the pile response. The failure mechanisms of the pile-slope system subjected to the pile locations, pile head conditions and pile length are each discussed. The contact pressure, shear force and moment along the piles are presented to illustrate the pile stabilising mechanism herein.

KEYWORDS:

• 3-D finite element analysis
• slope-stabilising piles
• Mohr–Coulomb
• strength reduction
• spacing effect
• coupled analysis

Acknowledgements

The author would like to thank Professor Schaefer and Sritharan of Iowa State University for their financial support to complete this research work. With their encouragement and support, this research can be done well. The author also would like to thank ND EPSCoR program to support the continuing research on this topic.

Disclosure statement

No potential conflict of interest was reported by the author.​​

Additional information

Funding

​​The author would like to thank Professor Schaefer and Sritharan of Iowa State University for their financial support to complete this research work.