Abstract：High strain rate uniaxial compressive loading tests on disk Barre granite(BG) samples were conducted by modified split Hopkinson pressure bar(SHPB) system with pulse shaping and momentum-trap technique. The samples were tested under X(intermediate P-wave velocity)，Y(lowest P-wave velocity)，and Z (highest P-wave velocity) directions. The dynamic stress equilibrium on both ends of the sample and constant strain rate was achieved during loading with help of pulse shaper(copper + rubber) technique. The momentum-trap technique was adopted to protect the sample from multi-loading by the incident bar. Corresponding to three loading levels，three damage levels of the rock samples were identified according to the extents of damage，namely，quaso-elastic，cracked，and fragmented samples. The damage assessment of recovered sample was investigated after cut to thin sections，and the microcrack increased with the loading rate. The stress-strain curves of samples at different strain rates(70，100，130 s－1) under three directions were obtained. The correlation between the failure modes and shape of the stress-strain curves was discussed. The maximum stress increased with the loading rate. The dynamic strength was isotropic at low and high strain rates，but Y-samples had the highest dynamic strength under middle loading rate. The XZ plane was considered to be parallel to the rift plane，thus it was difficult to split the cracks with the critical loading level.
