Structural control on fracture toughness (brittle cracking) in the Krosno Sandstones of Mucharz, southern Poland

Authors

  • Artur Dziedzic Faculty of Geology, University of Warsaw, Al. Zwirki i Wigury 93, PL-02-089 Warszawa, Poland

Keywords:

rock mechanics, fracture, anisotropy, crack propagation, ultrasounds

Abstract

The fracture toughness of the Krosno Sandstones of Mucharz, southern Poland, was analysed to determine, its relation to structural features of the rock, in particular as regards their orientation relative to the direction of the load applied. The critical stress intensity factor for fracture toughness KIC was determined according to the rarely used chevron bend method, as recommended by the International Society for Rock Mechanics (ISRM). Tests were carried out at constant load increase, equal to 15 kN/min.12 sandstone specimens, cut out in three mutually perpendicular directions from 4 cubical rock blocks, were analysed. The mutually perpendicular failure planes, obtained in this way relate to structural features of the rock material, making it possible to evaluate the effect of structure on the fracture pattern of the rock analysed. Toughness tests were preceded by measurements of propagation ultrasound waves and analysis of dynamic features that enabled preliminary determination of the rock anisotropy. The research elucidated the structural controls on the fracture toughness of the Krosno Sandstones.

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Published

2010-03-27

Issue

Vol. 47 No. 1 (2003)

Section

Articles

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