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Analysis of the dynamic behaviour of the hangingwall beam during a seismic event
Bibliography: leaves 68-72.
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| Format: | Thesis |
| Language: | English |
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Department of Mechanical Engineering
2014
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| _version_ | 1867613243396063232 |
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| access_status_str | Open Access |
| author | Daehnke, A |
| author2 | Martin, JB |
| author_browse | Daehnke, A Martin, JB |
| author_facet | Martin, JB Daehnke, A |
| author_sort | Daehnke, A |
| collection | Thesis |
| description | Bibliography: leaves 68-72. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/8383 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:01.081Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | Department of Mechanical Engineering |
| publisherStr | Department of Mechanical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/8383 Analysis of the dynamic behaviour of the hangingwall beam during a seismic event Daehnke, A Martin, JB Mechanical Engineering Bibliography: leaves 68-72. In a deep-level gold mine planes of weakness oriented parallel to the reef allow the hangingwall to separate from adjacent rock strata. The hangingwall then acts as a separate beam supporting only its selfweight. Mining-induced near vertical shear fractures divide the hangingwall beam into distinct blocks of relatively intact material. The objective of this study is to investigate the response of the isolated hangingwall beam during a seismic event. The study is particularly concerned with the global, resonant behaviour of the hangingwall and local shear or crushing failure of the rock at the shear fractures is not considered. A finite element program is developed to compute the hangingwall response during seismicity. The response is normalised, thus permitting the response spectrum method to describe maximum hangingwall motions during a seismic event at various beam lengths. By comparing the response spectrum describing a single-degree-of-freedom (SDOF) system with the spectrum of the hangingwall, it is evident that, although the hangingwall response spectrum is shifted to a higher frequency and velocity domain, the shapes of the two spectra are essentially the same. The frequency and velocity shift is calculated for 15 seismic events and empirical rules are developed to quantify the spectral shift for a wide range of event magnitudes. Unlike the spectrum describing hangingwall motions, the construction of a SDOF response spectrum is computationally cheap and is standard practice in earthquake engineering. By applying the empirical rules the seismologist can extrapolate the SDOF spectrum to estimate maximum hangingwall motions due to a seismic event and critical beam lengths which are prone to resonance. The effect on the response of the hangingwall supported by backfill consisting of dewatered and cemented tailings is evaluated. It is shown that a fill-to-face lag of less than 5m reduces hangingwall motions considerably. Further, at small strains the stiffer cemented tailings provide superior support than that offered by comparatively soft dewatered tailings. A chart is presented which correlates event magnitudes to critical beam lengths prone to resonance. 2014-10-11T12:16:25Z 2014-10-11T12:16:25Z 1992 Master Thesis Masters MSc http://hdl.handle.net/11427/8383 eng application/pdf Department of Mechanical Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Mechanical Engineering Daehnke, A Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| thesis_degree_str | Master's |
| title | Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| title_full | Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| title_fullStr | Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| title_full_unstemmed | Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| title_short | Analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| title_sort | analysis of the dynamic behaviour of the hangingwall beam during a seismic event |
| topic | Mechanical Engineering |
| url | http://hdl.handle.net/11427/8383 |
| work_keys_str_mv | AT daehnkea analysisofthedynamicbehaviourofthehangingwallbeamduringaseismicevent |