RESEARCH ON DYNAMIC FRACTURE TOUGHNESS AND TENSILE STRENGTH OF ROCK AT DIFFERENT DEPTHS
MAN Ke1，2，ZHOU Hongwei1
(1. Institute of Rock Mechanics and Fractals，China University of Mining and Technology，Beijing 100083，China； 2. Rock Mechanics Laboratory，Swiss Federal Institute of Technology Lausanne(EPFL)，Lausanne CH–1015，Switzerland )
Abstract：According to the standard test method suggested by ISRM and Standard for Test Method of Engineering Rock Mass(GB/T50266–99)，the dynamic fracture toughness and uniaxial tensile strength of the basalt specimens at different depths are measured. It is observed that there may be a certain relation between dynamic fracture toughness and tensile strength. From the point of view of rock failure mechanism，the essential reason for existing relation between dynamic fracture toughness and tensile strength is analyzed. Rock failure is due to the microcrack unstable propagation. The growth，propagation and coalescence of microcracks in rocks induced by tensile stresses lead to the failure of rock. It provides an easy method to estimate the dynamic fracture toughness by the tensile strength value according to the certain relation between dynamic fracture toughness and tensile strength. It will greatly simplify the dynamic fracture toughness test.
