Seismically induced landslide mitigation using flexible slope stabilisation systems

Following earthquake events multiple soil slope failures are observed throughout the structurally fragile soil and rock in North Island, New Zealand. Many of these slopes are located in close proximity to various assets including residential buildings and roads, resulting in damage to the structures. Limited mitigation solutions are available to stabilise both the global integrity and surficial slope-parallel instability along with surficial erosion of the slope. High-tensile steel mesh, combined with an underlying three-dimensional geotextile, provides an effective, economical alternative with a greater design life than shotcrete and massive retaining structures. The flexible mesh is tensioned across the slope with a dimensioned grid pattern of soil/rock nails that allows the system to be tailored to the site. Special concepts have been developed and are well proven for the dimensioning of the systems to consider superficial instabilities both slope parallel and in between the nails. The mesh promotes re-vegetation or greening of the slope for an aesthetically pleasing, natural looking finish. Numerous cases in New Zealand and internationally confirm that these measures are effective and practical for this application.