Seismic Technology For Slope Stability Investigation In Yeppoon North Queensland

Abstract

Slope instability has become one of the most significant geotechnical risks in recent times. Unfavourable geologic and climatic conditions, combined with anthropogenic activities, result in thousands of slope failures each year. Standard methods of geotechnical investigation such as boreholes and SPT-tests are not consistent in providing the geotechnical data for the site as a whole. Leaving engineers to assume the soil properties for most of the site, a disadvantage that may significantly increase the cost of remediation measures. Geophysics, in particular seismic surveying can provide alternative methods to solve this geotechnical problem. Although seismic surveys are widely used throughout the mining industry, it has not been applied to slope stability problems in Australia. This is mostly due to a lack of awareness, availability and acceptance/application of modern science. This paper seeks to establish the advantages of seismic methods in resolving slope instability issues. This paper illustrates the advantages of using seismic technology by presenting a case study, seismic technology for slope stability investigation in Yeppoon North Queensland. After significant rain in February 2008 a medium sized landslide occurred at the top of an embankment in the road reserve at Statue Bay, Yeppoon. The landslide regressed into the rear of the private properties above and therefore remediation measures were required. This is a reasonably standard geotechnical task, but when combined with steep vegetated slopes and very limited access, standard methods were not adequate. Seismic refraction and Multichannel Analysis of Surface Waves (MASW) surveying methods were used to generate 2D & 3D sub-surface images. These images distinctively illustrated the sub-surface material profiles, including the rock line and areas of slip prone material.