Engineering seismic refraction surveys over Elura

Abstract

In the early days, the Elura orebody was considered as a potential open pit mine. In order to evaluate the cost of overburden stripping, it was necessary to estimate the depth to which excavation could be carried out by ripping and scraping instead of the more expensive drill-blast-shovel and truck procedure that is used in a rock mass that is too strong to rip. The depth of economic rippability depends on: the size of the bulldozer and arrangement of the rippers being used; the rock substance strength; the orientation of major fractures such as shears and faults; the orientation, spacing, continuity and degree of interlock of the joints. It is common engineering practice to estimate rippability in terms of the capability of a Caterpillar D9 Bulldozer with single tyne hydraulic ripper. This is largely because of the pioneering work of the Caterpillar Company in the development of methods of estimation of rippability, particularly those involving seismic refraction as outlined in their handbooks. Other bulldozer and ripper systems are then evaluated by comparison with their performance relative to the D9.