(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. State Key Laboratory of Frozen Soil Engineering，Institute of Cold and Arid Regions Environment，and Engineering，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China)
Abstract：Loading rates can result in the change of rock¢s rupture shape. There is a critical velocity during the breakage process of material when plasticity transferring to brittleness. The numerical sample of rock is virtually performed by compiling program through embedded Fish language under particle flow code condition. Then，uniaixal compression tests with four kinds of loading rates，i.e. 0.000 5，0.001 0，0.005 0，0.050 0 m/s，are designed to study the loading rate effect. Moreover，the influences of rupture process，crack number and propagation，stress-strain curve，stress and strain，energy transformation done by loading rate are analyzed based on these tests. It is found that increase of loading rate ruins the advantageous shear zone¢s development，which makes the shear zone expanding with same velocity；and the material failure surface appears cone shape，in which the loading rate enhances the mechanical and deformation features of material at meso-scale，which makes the rock breaking into pieces；and that the rate causes energy loss increasingly，which is relevant to the ability of absorbing and dissipating energy from its mechanical behaviors.
