Effect of Various Rainfall Conditions on the Roadside Stabilisation of Slopes in Gippsland

A distinctive slope stabilisation method that integrates two well-developed methods for slope stabilisation is analysed in this paper. The slope stabilisation method utilises embedded piles and geogrid-reinforced retaining walls with gabion basket wall facing. To study the effect of this integrated slope stabilisation method on the stability of the slope under the negative impacts of rainfall, a three-dimensional finite element model with fluid–solid coupling is adopted to indicate the rainfall infiltration process and investigate the corresponding slope responses. The shear strength reduction method is applied after fluid–solid coupling analysis to investigate the impact of various rainfall intensities and rainfall patterns on the stability of slopes with different configurations. The results from the comparison of slope responses among various configurations indicate that under the highest rainfall intensity, the integrated method improves the stability of the slope up to 41.2 % and restrains the displacement increment of the road edge to a maximum of 12.5 mm. The most critical rainfall pattern for the stability of the slope has also been recognised in terms of the factor of safety and the variation in the negative pore-water pressure of the slope. The numerical results indicate that the back-loaded rainfall pattern always yields the lowest factor of safety and induces the highest loss of matric suction, which can be 23 kPa at the toe of the slope. Moreover, a comparison between two construction scenarios under various rainfall intensities was also conducted, which demonstrates that the reinforced filled slope configuration is preferable when the site conditions permit.