Jessica Vatcher disputerar vid LTU

PhD-student/researcher: Jessica Vatcher

Title of doctoral thesis: Listening to the Story of the Rock Mass

Room: A1547

Start: kl 10.00

Summary:

The need to understand rock mass behaviour has never been greater; as mining globally progresses, we encounter new rock behaviour issues. Engineers working in rock mechanics, however, are often left in the dark. Few guidelines exist in the literature as to which data should be collected, how they should be analysed, and what tools and techniques need to be used to understand the causes of mine-scale rock mass behaviour. The development of techniques to understand the rock mass can lead to significant improvements in mine safety and profitability.

 

This thesis examines how to listen to the story of the rock mass. The thesis is composed of techniques and methodologies to: 1) evaluate conventional and unconventional data related to the geomechanical environment, and 2) obtain a mine-scale, holistic understanding of the story of the rock mass. Data from Luossavaara-Kiirunavaara AB’s (LKAB) Kiirunavaara Mine was used to develop these ideas, however a strong focus was given to developing general methodologies that can be applied to many mining environments.

 

Through this work, the understanding of which data sources are useful from a geomechanical perspective has broadened. Techniques to develop 3-D geomechanical models have been expanded, and common characteristics of useful data sources have been identified. A methodology using numerical stress analysis to identify if geomechanical features are of significance to rock mass behaviour was developed, and successfully applied to the Kiirunavaara Mine. The analyses lead to a paradigm shift in the understanding of the rock mass behaviour at the Kiirunavaara Mine. While it was initially believed that mines-scale faults were the cause of much of the seismicity experienced at the mine, it is now understood that large volumes of clay alteration identified via this work are significantly influencing the stress field, and the resulting rock mass behaviour at the mine-scale. Future applications and developments of listening to the rock mass using a mine-scale, 3-D, and long-term perspective have the potential to lead to enhancements in our understanding of the story of each rock mass.