Physical and numerical modelling of pile-stabilised saturated layered slopes

Pile installation is slope stabilisation technique that can improve stability of multi layered slopes by providing passive forces. This paper presents the results of experimental and numerical models for the behaviour of isotropic and anisotropic pile-stabilised sandy slopes under surcharge loads. The aim is to determine the optimal arrangement of pile rows about factors influencing the response. Effects of various parameters on slope stability were studied: pile group length (h), pile rows' distance from slope toe (L-x), number of pile group rows (N0), embedded length of the piles in saturated soil (h '), internal friction angle of the soil (phi) and distance between pile rows (L-p). Results indicated that in slopes stabilised with N ' = 2, utilising one of the pile rows in the position of the slope toe or crest, or using these positions simultaneously, are rejected both technically and economically. Moreover, if the failure wedge does not reach the saturation layer level in anisotropic slopes, increasing N ' is not an appropriate choice. As a significant result, the coupling effect of L-p-L-x and size of soil grains also strongly influence the optimum arrangement of piles, so that augmentation in phi in larger L-p leads to an optimised design.