Instrumentation for slope stability - experience from an urban area

This paper describes the monitoring of several existing landslides in an urban area near Wollongong in the state of New South Wales, Australia. A brief overview of topography and geology is given and reference is made to the types of slope movement, processes and causal factors. Often the slope movements are extremely slow and imperceptible to the eye, and catastrophic failures are quite infrequent. However, cumulative movements at these slower rates do, over time, cause considerable distress to structures and disrupt residential areas and transport routes. Inclinometers and piezometers have been installed at a number of locations and monitoring of these has been very useful. The performance of instrumentation at different sites is discussed in relation to the monitoring of slope movements and pore pressures. Interval rates of inclinometer shear displacement have been compared with various periods of cumulative rainfall to assess the relationships.