ABSTRACT
Rock is well known as a kind of engineering geological material and there are usually some internal defects such as some random holes and cracks distributed in different size. Now numerical method has been widely used to reproduce the experimental results and some research results have confirmed that dynamic characteristics of the rock are related to the experimental conditions and the damage state. The dynamic experiment of the granite in Brazil was simulated by using the finite element theory and simulation results are close to the results of SHPB experiment (T. Saksala et al, 2013a), the uniformity of stress distribution in the process of SHPB numerical simulation was discussed (D.J.Frew, 2001 and M.Q.Li et al, 2010) and dynamic behaviour under different strain rate was simulated by SHPB numerical simulation method (Y. Hao and H.Hao, 2013), the effect of radial inertia on elastic samples was investigated during a valid SHPB test (M. J. Forrestal et al, 2007), several critical issues such as the choice of slenderness ratio of the compressive specimens and the effect of friction between the sample and bars on the measured results of compressive strength were discussed (F. Dai, et al, 2010). In addition, dynamic
2 PRE-DAMAGED TREATMENT OF ROCK
Firstly, some standard cylindrical specimens (50 × 100 mm) made up of sandstone were carried out uniaxial and triaxial quasi-static compression test respectively and confining pressure was set to 5MPa, 10MPa, 15MPa, 20MPa respectively under triaxial condition. The pre-damaged samples were obtained by stopping to load after the uniaxial compression yield limit, then the pre-damaged specimens are reload under different confining pressure that was set to 2MPa, 4MPa, 6MPa, 8MPa respectively, and at the same time rock specimens under different stress path were measured using a PHILIPS X-ray CT scan system. The CT value is proportional to the material density, the CT gray images of the 10th scanning layer in Fig. 1 show that the different density distribution and damaged status of initial and post-peak specimens under different stress.
