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- Alm, Ove, et al.
(författare)
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Microstructures and mechanical characteristics of the Tännäs augen gneiss, Swedish Caledonides
- 1980
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Ingår i: Geologiska föreningens i Stockholm förhandlingar. - : Informa UK Limited. - 0016-786X. ; 102:4, s. 319-334
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical behaviour, microstructure and substructure of the classic Tannas augen gneiss of the Swedish Caledonides are presented. Progressive deformation of granodiorite to augen gneiss and mylonite is shown to take place in an isochemical environment with redistribution of megacrysts to surrounding matrix. Experimental deformation of natural rocks from the Tannas Augen Gneiss Nappe has been carried out in the temperature range of 20-600oC and under confining pressure of 100-700MPa. The highest strength found is for the fine-grained mylonite. The augen of the gneiss show brittle behaviour under all test conditions, and temperature has a limited effect on the ultimate strength of the matrix of the augen gneiss. Microstructures have been analysed by means of optical microscopy and transmission electron microscopy. The progressive deformation is brought about by dislocation glide and dislocation creep. Subgrain formation, recrystallization and straining of new grains are observed at all stages of the progressive deformation of the matrix while the augen behavior is brittle
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- Bjarnason, B., et al.
(författare)
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New developments in hydrofracturing stress measurements at Luleå University of Technology
- 1989
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - : Elsevier BV. - 0148-9062 .- 1879-2073. ; 26:6, s. 579-586
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Tidskriftsartikel (refereegranskat)abstract
- Instrument and theoretical developments in hydrofracturing stress measurements at Lulea University of Technology since the first workshop in Monterey in 1981 are described and the general experience with the method in Sweden is summarized. A new field unit is described which includes a 1000-m long multihose and a 100 MPa water pump. Stress measurements by means of injection tests on preexisting fractures have been introduced and applied at two sites in Sweden. A theory has been developed which permits estimation of the maximum and minimum horizontal stresses in cases where transverse hydrofractures are created in the borehole wall instead of axial.
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| 7. |
- Bjarnason, Bjarni, et al.
(författare)
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The Bolmen project
- 1986
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Rapport (övrigt vetenskapligt/konstnärligt)
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- Björnfot, Folke, et al.
(författare)
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Interaction of grouted rock bolts and hard rock masses at variable loading in a test drift of the Kiirunavaara mine, Sweden
- 1984
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Ingår i: Rock bolting. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 9061915147 ; , s. 377-395
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Konferensbidrag (refereegranskat)abstract
- description is presented on the interaction between a reinforced drift and the surrounding rock. It attempts to explain the support mechanisms and characteristics of cement grouted rock bolts, as used in hard rock mining and underground construction. A 20 m long section of a test drift at the 514 m level in the Kiirunavaara Mine, was instrumented with 20 rock bolts mounted with strain gauges and linked to a data logger, and 50 bolts combined with single-anchor extensometer. Rock movements were measured with 23 borehole extensometers, 45 convergence measurement stations, and precise levelling. 14 stress monitors recorded changes in the tangential stresses in the surrounding rock mass.
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