Effect of Dimension Variables on the Behaviour of Slopes Stabilised by an Integrated Method Combining Gabion-Faced Geogrid-Reinforced Retaining Wall with Embedded Piles

Severe slope instability exists in the area of South Gippsland in Victoria state located in south-east Australia. An integrated slope-stabilisation method, which includes a pile-retaining structure installed at toe of the gabion-faced geogrid-reinforced retaining wall, has widely been used in this district. A continuous steel rail wall embedded in the concrete pile then provides lateral support to the retaining wall. The effectiveness of the integrated method is first illustrated by comparing the slope stability evaluated by strength reduction method and behaviours of the slope obtained by elastoplastic analysis. A series of parametric studies are then performed to investigate effects of facing inclinations, embedded geogrid length, and vertical spacing of geogrid layers on the stability and behaviour of the slope and the behaviour of the pile under various uniform surcharge load conditions. The numerical results indicate that additional contribution from piles can increase the stability of the slope up to 42.9%. The dimensional variables of gabion-faced geogrid-reinforced retaining wall also impose significant impact on the behaviour of slopes and piles, and the effect of each variable has also been quantitatively evaluated and qualitatively described. The effect of the geogrid amount on behaviours of slopes and piles has also been investigated through the comparison between two slope configurations with maximum and minimum geogrid amount. The results from the parametric studies can then be used as a design reference for the future applications of this integrated slope-stabilisation method.

Automated summary

Severe slope instability in South Gippsland, Victoria state, Australia has been effectively addressed using an integrated slope-stabilisation method. This method includes the installation of a pile-retaining structure at the toe of a gabion-faced geogrid-reinforced retaining wall, with lateral support provided by a continuous steel rail wall embedded in concrete piles. Parametric studies reveal that additional contribution from piles can significantly increase slope stability.