Challenge

Measurements of in-situ stress are part of rock mass characterization. This is the complex process that provides the mining companies with the information to identify the geotechnical risks and predict how a particular mine design might perform and enable the mining companies to act to avoid the risks in a timely manner. Poor rock mass characterization at the design, construction or production stages can lead, at best, to disappointing results for shareholders’ investments and, at worst, to fatal accidents in mines, as well as the closure of large mine areas.  

In situ stress information can be used to calculate the shear stress on the large-scale structures that are likely to be mobilized and cause failure around the underground excavations where people and machinery are exposed. Additionally, at some depth below surface, induced stress results in micro seismicity influencing the overall rock mass behavior at a mine scale. Hence, this information is critically important. 

Solution

Research at the WA School of Mines in Kalgoorlie has enabled the routine determination of in-situ stress either in active extraction areas or in remote regions that have no access from current mine workings, but where geotechnical data from diamond drill coring is widely available. Notably, measurements have been acquired in excess of 2000 metres from an existing excavation. This is a critical technology that has been named the WASM AE Methodology and provides companies with in-situ stress measurement from great depths that are not yet accessible but can be designed prior to access infrastructure and personnel exposure. 

The WASM AE methodology has been available to the civil and mining industries though an agreement with Mining3, with more than 500 in-situ stress measurements undertaken to date.