Pile contribution to slope stability: application to open quays

Abstract

Foundation piles can contribute to the stability of a slope thorough which they are installed as they have to be sheared or fail in bending for the full collapse of the slope. The classical design of open quays, consisting of a piled platform with a slope beneath, can benefit from the consideration of the piles for its overall stability. The methods currently available for the consideration of piles are the limit equilibrium method (LEM) and the finite-element method. Although the former requires some side computations for the pile contributions, it has the advantage of identifying the failure mode. This can be used to make changes to the piling design in order to increase pile contribution to stability. The LEM approach, by Bishop's method, which considers circular slip surfaces, is particularly practical. A typical quay is studied with both approaches and the main parameters of such projects – pile density, slope angle and soil shear strength – are evaluated. The results of the analyses indicate that the consideration of the piles leads to an increase in the factor of safety of the slope. It is also suggested that the LEM approach can be used to advantage in everyday practice.