Abstract

ANDERSEN, N.. Pre-sink shaft safety analysis using wireline geophysics. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.5, pp.435-439. ISSN 2411-9717.

During the preliminary design phases and feasibility study of a proposed vertical shaft, a vertical diamond drill-hole is normally drilled on the site. This paper outlines how rock mass characteristics, in-situ rock stress, rock strength, hydrological characteristics, and structural parameters can be determined using wireline logging of this borehole. In addition, a rock mass classification scheme is developed, based on published work, and in particular the Q-factor is adapted to assess the stability of raise-bored shafts. The 'stick plot' is introduced, which combines all geotechnical parameters applicable to the stability of a vertical shaft into a colour-coded format where cross-correlations can readily be made on a day-today basis during the shaft-sinking process.

Keywords : shaft-sinking; raise-boring; geophysical logging; geotechnical; Q-factor; stability.

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