LAUSR

Slope instability is a common geotechnical issue in South Gippsland, Victoria, Australia. The network of rural roads constructed and maintained by the local authority are greatly affected by the instability. An integrated slope-stabilisation system that combines two well-developed slope stabilisation methods has been used widely in this district. These two methods are gabion-faced geogrid-reinforced retaining wall and pile retaining structures. These two methods are connected by a steel rail that is welded at the top of the piles to buttress the lowest row of the gabion basket wall. In order to reflect the site conditions accurately, a three-dimensional non-linear finite element approach is adopted in this study. The elastic-perfectly plastic constitutive model with the Mohr-Coulomb yield criterion is used to describe the behaviour of the soil and the gabion basket. With the assistance of the shear strength reduction technique, the effectiveness of the integrated system is demonstrated through the comparison of the representative indicators of the slope stability among various slope configurations. A series of parametric studies related to the ratio of the embedded length of geogrid to the height of the slope, the ratio of the embedded length of the pile to the thickness of the unstable soil layer, and the ratio of the spacing to the diameter of the pile have also been conducted for the purpose of optimising this slope stabilisation infrastructure. The results from the parametric studies indicate that the optimised and improved integrated infrastructure can stabilise the road and slope economically without the loss of the safety margin.