Journal of Surveying Engineering

A gravimetric geoid model does not allow the accurate transformation of Global Positioning System (GPS) ellipsoidal heights to Australian Height Datum (AHD) heights in the Perth region of Western Australia. This is predominantly due to the effect of the geological structures associated with the Darling Fault, the availability and quality of data, and the possibility of distortions in the AHD. Therefore a combined solution is sought, where 99 colocated GPS and AHD heights are used to adjust the gravimetric geoid such that it provides a model of the separation between the AHD and the GRS80 reference ellipsoid. This data combination was investigated using least-squares collocation and continuous curvature splines in tension. The least-squares collocation technique was found to give an improved model of the AHD–GRS80 separation, as shown by a standard deviation of fit of the combined model to the control data of ±8 mm. In comparison, the gravimetric geoid gives a standard deviation of fit to the control data of ±128 mm.

Monitoring the deformation and other useful physical parameters of slopes, either natural mountain slopes or those formed in open pit mining or construction, is one of the most effective methods to avoid or reduce the risk caused by landslides. The commonly used geotechnical instruments for slope monitoring in the Australian open pit mining industry are first reviewed briefly, then followed by the introduction of an automatic slope monitoring system that is based on integration of electronic geotechnical instruments with specialized software. The design and test results of the system at a mining site in Australia are given in detail. It is shown from the test and a critical assessment of the system that automatic monitoring of slopes offers a number of advantages over manual data-gathering approaches.