Geotechnical Back Analysis
The Geotechnical Design Process relies heavily on effective Back Analyses to ensure the quality of the design. This is a necessary step in the design process because of the natural variability of the rockmass.
Geotechnical back analysis refers to any investigations, analyses or studies which aim to confirm that the current data and observations correlate with the forecasted data from the implemented design. This also includes evaluating the effectiveness of control measures (seismic re-entry, TARPs etc.) and the effectiveness of analysis results (seismic hazard etc.).
“Companies, where regular back-analysis practices are lacking, have an uncertain risk profile, and this could lead to severe financial and safety consequences which might not be clear to the company management and investors at the time.”
From Becker (2010)
SRMP from the Australian Centre for Geomechanics
If back analysis is not a regular part of the design process, even the best geotechnical designs will either become overly conservative or unsafe. This change in the effectiveness of the geotechnical design, in many cases, is not clear until it is too late.
Companies, where regular back-analysis practices are lacking, have an uncertain risk profile. This could lead to severe financial and safety consequences which might not be clear to the company management and investors at the time. A good recent example of this is the failure of tailing dams from several companies, because of the lack of adequate back analysis and monitoring regimes.
Mine sites with good back analysis practices have the following in common:
All assumptions and input parameters (rockmass UCS, stress orientations, stress values etc.) used in the geotechnical design are clearly recorded and easily accessible.
All high-risk areas identified by the geotechnical design and the expected rockmass behaviour in those areas, are described in terms of measurable expectations (stress, deformation, damage etc).
The geotechnical monitoring program (extensometers, lidars, seismic system etc.) is guided by the expected rockmass behaviour based on the geotechnical design.
Regular back-analysis investigations are done, and any unexpected results are investigated and documented.
Unwanted events or unexpected monitoring results leads to adjustments in the geotechnical design.
With a successful back analysis process, the geotechnical design is optimised which has a positive impact on the company, and ensures:
Confidence in the geotechnical risk profile and design process
Optimisation of the geotechnical design, which leads to
Improved safety
Long-term cost reduction
Any shortcomings are identified, and it allows time to investigate, improve or implement alternative controls
Are back analyses done often on your Mine site? If not contact us now and we can assist you with the process. IGM Geotechnical, Expert Underground Geotechnical Engineers.