Abstract: The mechanical properties of coal changing with the strain rate are proposed by impact uniaxial compression tests on split Hopkinson pressure bar (SHPB) equipment which with a diameter of 50 mm. Six different strain rates are provided for coal by designing test pressure levels with 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55 MPa. Results of the tests are indicated as follows：Stress- strain curves of coal at high strain rates can be roughly divided into compaction phase, elastic deformation stage, micro- cracks evolution stage, crack unstable growth stage and unload stage. What’s more, increased strain rate can shorten compaction phase and extended elastic deformation stage. With the increase of strain rate, the increment of dynamic elastic modulus and peak stress of coal can be approximately represented by a logarithmic trend, while decrement of the peak strain approximate logarithmic form. The damage extent of coal sample increases with the increasing strain rate, which becomes the most significant when strain rate increases from 68.666 s-1 to 79.751 s-1.The results can be provided the basis for determining the rationalized parameters of cutting coal mining engineering.

Key words: high strain rates, mechanical properties of coal, impact load, mining engineering