Analyse der Gebirgsdrucksituation für einen querschlägigen und streichenden Abbauzuschnitt im Revier VI des Magnesitbergbaus Breitenau

Translated title of the contribution: Analysis of the rock pressure situation for a transverse and striking mining layout in Revier VI of magnesite mine Breitenau

Benedikte Moosbacher

Research output: ThesisMaster's Thesis

Abstract

Due to the increasing demand for raw materials as a result of population growth and the depletion of near-surface deposits, it becomes necessary to mine deeper deposits. However, with the advance to greater depths, the primary stresses also increase, and the control of rock pressure becomes central. To adequately supply society and at the same time ensure economic, sustainable and, above all, safe mining, it is essential to overcome the specific conditions and challenges associated with increasing depth. This thesis considers the Breitenau magnesite mine, which is expanding its mining operations further to greater depths. As the depth increases, so does the complexity of the mining process at Breitenau. Mining in the Westfeld is done via sublevel stoping. Special attention is paid in this paper to the planned expansion in mining district, Revier VI. A rotation of the stope orientation from 75° (in striking direction), which corresponds to the current orientation of the Westfeld, to 140° (in transverse direction) is analysed. Both mining layouts are compared to analyse the effects regarding the stresses and conditions of the drifts. For this purpose, the in-situ conditions of the drifts in the Westfeld were recorded at the beginning of this work. Subsequently, linear elastic numerical simulations of the Westfeld were carried out. Therefore, one stope after the other was mined according to the real sequence in the simulations. During the mining process, the stope pillars get overloaded and de-stressed afterwards. To reproduce this effect in the numerical analysis, the stope pillars were made "soft", e.g., the stresses of the stope pillars were set to zero and a new Young´s -modulus (determined during calibration) was applied. The adjustment of the primary stresses and the Young´s modulus was carried out via the back analysis or calibration. The RCF value was calculated from the major and minor principal stresses of the numerical simulations and compared with the observed drift conditions. This process was repeated until the conditions on site were reproduced by the numerical simulations and the appropriate states or values of the primary stresses and the modulus of elasticity were found. It should be noted here that only the final state of the drifts was considered. This was followed by the forward analysis, e.g. the knowledge gained was applied and simulated for the two variants of the extension, namely in strike or transvers direction. The same material parameters and simulation process were selected. Different variants were analysed regarding the sequences. The two mining variants were analysed regarding the change in stresses and conditions in the drifts over the course of the individual mining steps (sequence). In addition, sensitive areas of the long-term infrastructure and barrier pillars were analysed in detail. The combination of numerical simulation and calibration makes it possible to forecast the stress states, stress distributions and expected drift conditions. This in turn makes it possible to make modifications to the stope design at an early stage.
Translated title of the contributionAnalysis of the rock pressure situation for a transverse and striking mining layout in Revier VI of magnesite mine Breitenau
Original languageGerman
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Wagner, Horst, Supervisor (internal)
  • Gams, Patrick, Co-Supervisor (internal)
Award date28 Jun 2024
Publication statusPublished - 2024

Bibliographical note

embargoed until 15-04-2029

Keywords

  • Rock Mechanics
  • Numerical Simulations
  • Deep Mining
  • Rock Stress
  • Stress Changes

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