DETERMINATION OF ELASTIC MODULUS，TENSILE STRENGTH AND FRACTURE TOUGHNESS OF BRITLE ROCKS BY USING FLATTENED BRAZILIAN DISK SPECIMEN——PART II: EXPERIMENTAL RESULTS
Abstract： Based on the results of theoretical analysis in part I of this paper，flattened Brazilian disk specimens made of marble were tested by compressive load applied on the flattens. The experimental results show that the elastic modulus ，tensile strength and fracture toughness of brittle rocks can be determined from a valid load-displacement record. The criteria for a valid test are：(1) the crack is initiated from the center region of the specimen，and propagates essentially along the vertical diameter till the critical point，(2) the fracture process after the maximum load，which is characterized by the load descending and then ascending，can be recorded in the test，however the ascending load does not surpass the previous maximum load. The size effect on is discussed based on the cohesive crack model. The modified fracture toughness considering the effect of fracture process zone is obtained by using Bazant′s size effect law.
