TY - BOOK

T1 - A contribution towards the practical implementation of stress management concepts in underground mining

AU - Ladinig, Tobias

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - The extraction of excavations disturbs the primary stress field and causes stress and energy changes in the rock mass. Highly stressed and de-stressed zones form and seismic energy is released. As mining progresses to greater depths, the primary stress magnitudes rise and hence the intensity of the stress and energy changes increases and rock pressure phenomena, such as stress driven fracture and failure or rock burst damage, start to occur. The severity of rock pressure phenomena increases with depth due to the rising primary stress magnitudes. If rock pressure phenomena become so severe that they endanger the objectives of mining, which are the safe, as complete as possible and economic mineral extraction, they are referred to as rock pressure problems. Rock pressure problems occur frequently in deep mining conditions. In these conditions the control of rock pressure is central for a successful operation. The present research work concentrates on rock pressure control in deep mining. The causes and consequences of rock pressure phenomena and rock pressure problems as well as applied strategies addressing them are reviewed and discussed. It is found that a passive strategy, which aims on alleviating the consequences of rock pressure problems, is dominating. In contrast, an active strategy, which tackles the sources of rock pressure problems to prevent their occurrence and which is therefore considered to be superior, is not widely utilized for different reasons. One reason is a shortage of applicable active strategies for many mining environments in particular for steeply dipping or massive deposits. This shortage of applicable active stress control strategies is addressed by proposing a stress management concept. The stress management concept relies on elements, which provide in isolation or in combination certain functions. Main elements are excavations, pillars, loading systems and time. The first three elements describe the mine layout and the fourth element describes the mining sequence. Hence, the proposed stress management concept is four-dimensional. The physical effects of the main elements and the element functions, which are based on these physical effects, are investigated. For the implementation of the concept the elements and their functions must be combined in a systematic way to control the rock pressure situation and to eliminate potential sources of rock pressure problems. Therefore, different mine layouts and mining sequences are proposed and analyzed as well as critical issues and open points for their application are highlighted. In the proposed layouts and sequences de-stressed zones are created in the deposit in the so-called de-stressing phase. The provided de-stressed zones are then utilized to protect infrastructure and stopes from rock pressure in the subsequent production phase, in which large-scale mineral extraction takes place. Furthermore, designated, specifically designed structures and mining sequences provide additional control of the rock pressure situation in both phases. Relevant aspects of the proposed layouts and sequences are first discussed on a conceptual basis. Then their application based on raise mining in steeply dipping or massive deposits is demonstrated. A case study in Kiruna mine, which highlights the application potential and advantages of the stress management concept, is conducted as well. In summary, the investigations show that the proposed stress management concept offers significant advantages and hence that its application facilitates or in certain situation even enables the safe, as complete as possible and economic mineral extraction at great depth.

AB - The extraction of excavations disturbs the primary stress field and causes stress and energy changes in the rock mass. Highly stressed and de-stressed zones form and seismic energy is released. As mining progresses to greater depths, the primary stress magnitudes rise and hence the intensity of the stress and energy changes increases and rock pressure phenomena, such as stress driven fracture and failure or rock burst damage, start to occur. The severity of rock pressure phenomena increases with depth due to the rising primary stress magnitudes. If rock pressure phenomena become so severe that they endanger the objectives of mining, which are the safe, as complete as possible and economic mineral extraction, they are referred to as rock pressure problems. Rock pressure problems occur frequently in deep mining conditions. In these conditions the control of rock pressure is central for a successful operation. The present research work concentrates on rock pressure control in deep mining. The causes and consequences of rock pressure phenomena and rock pressure problems as well as applied strategies addressing them are reviewed and discussed. It is found that a passive strategy, which aims on alleviating the consequences of rock pressure problems, is dominating. In contrast, an active strategy, which tackles the sources of rock pressure problems to prevent their occurrence and which is therefore considered to be superior, is not widely utilized for different reasons. One reason is a shortage of applicable active strategies for many mining environments in particular for steeply dipping or massive deposits. This shortage of applicable active stress control strategies is addressed by proposing a stress management concept. The stress management concept relies on elements, which provide in isolation or in combination certain functions. Main elements are excavations, pillars, loading systems and time. The first three elements describe the mine layout and the fourth element describes the mining sequence. Hence, the proposed stress management concept is four-dimensional. The physical effects of the main elements and the element functions, which are based on these physical effects, are investigated. For the implementation of the concept the elements and their functions must be combined in a systematic way to control the rock pressure situation and to eliminate potential sources of rock pressure problems. Therefore, different mine layouts and mining sequences are proposed and analyzed as well as critical issues and open points for their application are highlighted. In the proposed layouts and sequences de-stressed zones are created in the deposit in the so-called de-stressing phase. The provided de-stressed zones are then utilized to protect infrastructure and stopes from rock pressure in the subsequent production phase, in which large-scale mineral extraction takes place. Furthermore, designated, specifically designed structures and mining sequences provide additional control of the rock pressure situation in both phases. Relevant aspects of the proposed layouts and sequences are first discussed on a conceptual basis. Then their application based on raise mining in steeply dipping or massive deposits is demonstrated. A case study in Kiruna mine, which highlights the application potential and advantages of the stress management concept, is conducted as well. In summary, the investigations show that the proposed stress management concept offers significant advantages and hence that its application facilitates or in certain situation even enables the safe, as complete as possible and economic mineral extraction at great depth.

KW - Gebirgsmechanik

KW - tiefer Bergbau

KW - Untertagebau

KW - Raise Mining

KW - Gebirgsdruck

KW - Gebirgsdruckproblem

KW - Spannungsmanagement

KW - Abbaustrategie

KW - Abbauplanung

KW - rock mechanics

KW - deep mining

KW - underground mining

KW - raise mining

KW - rock pressure

KW - rock pressure problem

KW - stress management

KW - mining strategy

KW - mine design

M3 - Doctoral Thesis

ER -