New data on mode II fracture toughness of rock from the punch-through shear test

摘要: The Punch-Through Shear (PTS) test was introduced as a method to determine the ModeII fracture toughness of rock material (Backers et al., 2002). Its unique feature is ability apply confining pressure independent Mode II (shear) loading. This contribution reports new data on toughness', KIIC, dependency pressure, loading rate, sample size, and cyclic for six different rocktypes. Samples are subjected pressures up 70 MPa. KIICincreases with increasing tends reach constant value at higher than 20-35 Evidence 'pure' fracturetoughness high reported. Variation rate over five orders magnitude (10-8 - 10-3 m/s) does not change KIIC. influence size coarser grained rocks verified. Cyclic illustrates stiffness system propagation takes place. It concluded that PTS- suitable future KIICtermination.