The performance of mechanical anchors in South African mechanized deep level gold mining

Most of South African mechanized and semi-mechanized gold mines in the Witwatersrand basin are operating at depths ranging from 2.7–3 km below the earth surface. Before a tunnel is excavated, the underground stress distribution is uniform (ignoring tectonics) and the magnitude of vertical stress inc...

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Main Authors: Sengani, F., Zvarivadza, T.
Format: Book chapter
Language:English
Published: CRC Press 2022
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Online Access:https://doi.org/10.1201/9781351181327
http://hdl.handle.net/11408/4887
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author Sengani, F.
Zvarivadza, T.
author_facet Sengani, F.
Zvarivadza, T.
author_sort Sengani, F.
collection DSpace
description Most of South African mechanized and semi-mechanized gold mines in the Witwatersrand basin are operating at depths ranging from 2.7–3 km below the earth surface. Before a tunnel is excavated, the underground stress distribution is uniform (ignoring tectonics) and the magnitude of vertical stress increases proportionally to the depth. But once a tunnel is created, the portion of the strata directly above the tunnel loses its original support and the stress equilibrium is disturbed. The hanging wall starts to sag under the gravitational force. As a result; most of the mines prefer to install mechanical anchors as their reinforcement system within the tunnels, with the aim of improving the stability of the tunnel. This paper aims to evaluate the performance of mechanical anchors in deep level gold mining. Laboratory tensile tests were performance, followed by underground pull tests to determine the performance of mechanical anchors in different conditions. The results obtained from tensile tests have shown that mechanical anchors of 18 mm diameter cable, 4.5 m length, with six strands, can withstand a minimum load of 332 kN and the maximum load of 3441 kN, with a minimum displacement of 98 mm and maximum displacement of 105 mm. Underground pull test results showed similar results or closely related results. Kinematic analysis showed that there were six joint sets around the tunnel, this was confirmed using DIPS software (Stereonet). However, the six joint sets were found to create large wedges along the sidewalls of the excavation, this was confirmed using Un-wedge software.
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spelling ir-11408-48872022-06-28T07:06:41Z The performance of mechanical anchors in South African mechanized deep level gold mining Sengani, F. Zvarivadza, T. mechanical anchors Gold mining Gold mines Most of South African mechanized and semi-mechanized gold mines in the Witwatersrand basin are operating at depths ranging from 2.7–3 km below the earth surface. Before a tunnel is excavated, the underground stress distribution is uniform (ignoring tectonics) and the magnitude of vertical stress increases proportionally to the depth. But once a tunnel is created, the portion of the strata directly above the tunnel loses its original support and the stress equilibrium is disturbed. The hanging wall starts to sag under the gravitational force. As a result; most of the mines prefer to install mechanical anchors as their reinforcement system within the tunnels, with the aim of improving the stability of the tunnel. This paper aims to evaluate the performance of mechanical anchors in deep level gold mining. Laboratory tensile tests were performance, followed by underground pull tests to determine the performance of mechanical anchors in different conditions. The results obtained from tensile tests have shown that mechanical anchors of 18 mm diameter cable, 4.5 m length, with six strands, can withstand a minimum load of 332 kN and the maximum load of 3441 kN, with a minimum displacement of 98 mm and maximum displacement of 105 mm. Underground pull test results showed similar results or closely related results. Kinematic analysis showed that there were six joint sets around the tunnel, this was confirmed using DIPS software (Stereonet). However, the six joint sets were found to create large wedges along the sidewalls of the excavation, this was confirmed using Un-wedge software. 2022-06-28T07:06:41Z 2022-06-28T07:06:41Z 2018 Book chapter 9781351181327 https://doi.org/10.1201/9781351181327 http://hdl.handle.net/11408/4887 en Rock Dynamics – Experiments, Theories and Applications: Proceedings of the 3rd International Confrence on Rock Dynamics and Applications (RocDyn-3), June 26-27, 2018, Trondheim, Norway, Edited By Charlie C. Li, Xing Li, Zong-Xian Zhang; open CRC Press
spellingShingle mechanical anchors
Gold mining
Gold mines
Sengani, F.
Zvarivadza, T.
The performance of mechanical anchors in South African mechanized deep level gold mining
title The performance of mechanical anchors in South African mechanized deep level gold mining
title_full The performance of mechanical anchors in South African mechanized deep level gold mining
title_fullStr The performance of mechanical anchors in South African mechanized deep level gold mining
title_full_unstemmed The performance of mechanical anchors in South African mechanized deep level gold mining
title_short The performance of mechanical anchors in South African mechanized deep level gold mining
title_sort performance of mechanical anchors in south african mechanized deep level gold mining
topic mechanical anchors
Gold mining
Gold mines
url https://doi.org/10.1201/9781351181327
http://hdl.handle.net/11408/4887
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