Title: STUDY OF THE EFFECT OF MOISTURE CONTENT AND BENDING RATE ON THE FRACTURE TOUGHNESS OF ROCKS |
Authors: Vavro Leona and Souček Kamil |
DOI: 10.13168/AGG.2013.0025 |
Journal: Acta Geodynamica et Geomaterialia, Vol. 10, No. 2 (170), Prague 2013 |
Full Text: PDF file (2.0 MB) |
Keywords: fracture toughness, bending rate, tensile strength |
Abstract: Generally, rock material failure is controlled by cracks under specific conditions. The study of rock fracture toughness
belongs to the current frequent directions of research in the area of rock failure. The present paper describes the effects of
parameters influencing the resultant properties of rock materials (bending rate, rock moisture) during fracture toughness
measurement of different kinds of rocks (sandstone, marble, granite). The highest fracture toughness values were found in the
marble samples. This is probably due to the inner structure of analysed marble, which is composed of only one mineral
(calcite) and also has a lower porosity than the used granite. The lowest fracture toughness values were found in the sandstone
sample, and reached c. 17–30 % of the measured fracture toughness values of the analysed granite and marble samples. As in
the case of the other mechanical properties of rocks (e.g. uniaxial compressive strength) also in the case of higher sandstone
(carboniferous) moisture the fracture toughness values decrease and its deformation ability increases.
Preparation of samples for fracture toughness tests and performance of these tests are more complicated than in the case of
tensile tests (e.g. the Brazilian test) and therefore this contribution presents a comparison between fracture toughness of
analysed rocks and tensile strength values. The measured data in this study considering the fracture toughness tests and
Brazilian tests were compared with results published by Zhang (2002). |