ABSTRACT
There are large amount of random cracks in engineering rock. And the load acted position may be apart some distance from crack location and not act along the crack propagation direction (Pan et al. 2012). Thus, this paper used the Mechanical Testing Simulation system to perform granite threepoint bending test with different offset notches for the in-situ observation. The study has investigated the failure characteristics and crack development mechanism as well as different crack offset distances influence on fracture property. In addition, comparing to the experimental methods proposed by many domestic and foreign scholars, this paper has conducted the test making the existing crack
1 INTRODUCTION
With the greater depth of the underground projects, numerous research have continually entered into underground space such as deep tunnel, coal mining, underground storage of nuclear waste and geological storage of carbon dioxide as well as shale gas exploitation (Cai M et al. 2004, Molli G et al. 2010, Jordan K. Eccles et al. 2012). Thus, the investigation of underground space is of vital importance. Due to the simple underground environment and low field stress of tens of meters under the ground, geological investigation and exploration are enough for the well run of the underground engineering. However, the underground environment will be more complicated as the human being development going into thousands of meters depth of underground space. Deep rock mass or human engineering is violently affected by the complicated mechanical environment including high stress, high temperature, high karsts water pressure and intense exploitation disturbance (He et al. 2012, K. Khan et al. 2000).
