BOUNDARY ELEMENT ANALYSIS FOR STANDARD SPECIMEN CONFIGURATIONS IN THE ISRM SUGGESTED METHODS FOR DETERMINING FRACTURE-TOUGHNESS OF ROCK

In order to provide an analytical basis for the current "Suggested Methods for Determining the Fracture Toughness of Rock" [1] (referred to hereafter as Suggested Methods) proposed by ISRM, a 3-D boundary element analysis was carried out for standard configurations of two specimen types: chevron bend and short rod. From the results, it is shown that the non-dimensional stress intensity factor described in the Suggested Methods for the chevron bend specimens is approx. 10% greater than that determined in this work. This new calibration constant gives a more realistic fracture toughness for Ogino tuff. Good agreement was obtained with the Suggested Methods for the short rod specimen.