Relating measured deformation to support load

Authors: Milne, DM Download Paper

DOI https://doi.org/10.36487/ACG_rep/1925_05_Milne

Cite As:
Milne, DM 2019, 'Relating measured deformation to support load', in J Hadjigeorgiou & M Hudyma (eds), Ground Support 2019: Proceedings of the Ninth International Symposium on Ground Support in Mining and Underground Construction, Australian Centre for Geomechanics, Perth, pp. 101-108, https://doi.org/10.36487/ACG_rep/1925_05_Milne



Abstract:
This research looks at linking the magnitude and location of field deformation to the load on cable bolt support as it approaches failure. There has been a significant body of research conducted on the behaviour of cable bolt support in underground mining, especially in the 1980s and 1990s. This research has primarily concentrated on determining the critical cable pull-out strength based on the peak loads that can be mobilised through friction between the cable to grout interface. This paper looks at the case where adhesion and friction are both contributing to the cable to grout bond, before movement of the free end of the cable. It should be noted that when peak load is considered, a factor of safety may be applied to account for uncertainties with cable bolt pull-out strength. This work relating cable load to field deformation, can be augmented by techniques developed to extrapolate limited, discrete, field deformation to an overall surface deformation pattern. Field deformation is easily measured with extensometers and further information can be gained with borehole cameras. In some cases, such as in foliated or bedded hanging walls, beam or plate type deformation occurs and the magnitude of deformation, can be tied to opening geometry. This can enable localised information on deformation, collected by extensometers, to be extrapolated to areas without instrumentation coverage, which can then be related to a distribution of cable load.

Keywords: field deformation, extensometers, cable bolts

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