The Role of Geotechnical Engineering in Mining
What is geotechnical engineering in mining?
Geotechnical engineering is the discipline concerned with the engineering behaviours of earth materials. It uses the principles of soil and rock mechanics to form a solution for engineering problems. Principally, geotechnical engineers are involved in the investigation, design, and monitoring of open pit and underground mines. Geotechnical engineers are also involved in the design of waste dumps, tailings storage facilities and stockpile design, as well as backfill placement in underground operations.
Geotechnical engineering aims to ensure the safe design of pits and underground excavations by providing design parameter recommendations made through the analysis of rock mass properties generated by site investigation and rock mass sample testing. Through multidisciplinary input from hydrogeologists and mine planning engineers, an optimal design geometry and support implementation recommendations can be made to ensure the safety of the workforce whilst maximising ore recovery and reducing costs.
Why is it important?
Geotechnical engineering is one of the key, modifying factors required under the JORC Code (2012) and forms an integral part of mining, from scoping studies through to operational mines. The consideration of geotechnical engineering has become increasingly important over the past few decades as mines look to extract metals from deeper under the earth’s surface, reduce stripping ratios by steepening pit angles, and reduce waste rock tonnes. This provides a set of geotechnical challenges that require accurate data collection and analysis to produce safe excavation designs.
Simply put, a mining operation that does not identify or react to potential geotechnical risk to a project can have catastrophic effects for both worker safety and finance.
Recent project work
Recently, our team has been involved in supporting our client’s proposed underground mine. This included performing a gap analysis on the existing geotechnical data to identify gaps in the geotechnical model which needed to be addressed in order to meet the standards of a nominal Feasibility level study under the JORC code. We produced a proposed geotechnical drill programme and outline of the geotechnical data to be collected.
Wardell Armstrong International (WAI) were also involved in providing oversight of some of the data collection activities on site including borehole drilling, core logging, and acoustic televiewer surveys. Our team visited the project site to observe the client’s data collection process and suggest changes to improve data collection.We provided the client with a suite of recommendations to bring their data collection in line with the internationally recognised best practice given by the ISRM. Recommendations included
- Marking up discontinuities and photographing core at the drill rig as each length of core is recovered;
- Marking up mechanical fractures created by the drillers as they are formed; and
- Proper core storage in a core shed, with a proposal to use existing site infrastructure.
What does WAI have to offer?
As part of the Mining team, WAI can provide geotechnical engineering support to various stages of the mining process, specifically mining geotechnical investigation, underground rock mechanics, pit slope stability, geotechnical numerical modelling, and operational support. Geotechnical engineering is a dynamic discipline, and often requires input from our multi-disciplinary team, particularly the hydrogeologists, geologists and mining engineers, working as a team to provide engineering solutions to the mining industry.