Size effect in true mode <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1992" altimg="si156.svg"><mml:mi mathvariant="normal">II</mml:mi></mml:math> fracturing of rocks: Theory and experiment

The influence of specimen size on the measured values true mode II fracture toughness (KIIc) rocks have been investigated both experimentally and theoretically. In experimental study, double-edge notched Brazilian disk (DNBD) test is utilised to perform experiments with various radii ranging from 27 101 mm. Test results demonstrate a significant increase KIIc size. reason for this trend explained by novel mathematical model developed based process zone energy release rate (ERR) concepts. Comparing predictions theoretical data reveals that proposed theory can accurately predict effect phenomenon in DNBD data. To compare KIc, similar analyses are also performed I tests using semi-circular bend specimens. Lastly, we present set correction factors as functions size, whereby making it possible estimate independent value obtained laboratory