DBPapers
DOI: 10.5593/SGEM2015/B13/S3.051

INFLUENCE OF HEIGHT-TO-DIAMETER RATIO SAMPLES AND HUMIDITY ON THE GEOMECHANICAL PROPERTIES OF SANDSTONES

M. Bukowska
Friday 7 August 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-33-9 / ISSN 1314-2704, June 18-24, 2015, Book1 Vol. 3, 391-398 pp

ABSTRACT
Knowledge of behaviour of rocks subjected to load, in the full range of their deformation, is used in designing and then running underground mining operations. It mainly refers to efficiency of the operations and assessing probability of geodynamic phenomena in the rockmass. An important research problem is assessing influence of water and slenderness ratio of samples on geomechanical properties of Carboniferous rocks of Upper Silesian Coal Basin, Poland. Natural moisture of the rocks forming the rockmass is modified through dewatering and influences of mining operations. The state of capillary saturation reflects conditions of rocks in the mined rockmass the best. Geomechanical properties of the rocks were determined in laboratory conditions following the ISRM’s recommendations and own procedures. A total of 36 sandstone samples of slenderness ratio of 1 and 2 were prepared for the tests. The samples were loaded in servo-hydraulic testing machine MTS 810 NEW with the force acting perpendicularly to their bedding. The machine was controlled with the piston displacement at the rate of 0.005 mm/sec. Fine-grained and coarse-grained sandstones of Ruda Beds and Saddle Beds of Upper Carboniferous of Upper Silesia Coal Basin, Poland, were tested. Values of geomechanical parameters were determined basing on the full stress-deformation characteristics. These are strength parameters - uniaxial compression strength, residual strength and tensile strength. Uniaxial compression strength of sandstones shows decreasing tendencies for the increase in both slenderness ratio of samples and their moisture. For residual strength there were irregular changes depending on slenderness ratio and moisture of the samples. The value of tensile strength decreased by over ten per cent.

Keywords: slenderness ratio of samples, humidity, strength parameters, sandstones, Upper Silesian Coal Basin