Abstract:In order to get the quantitative description index of cracks and the relation between the index and strength parameter during the study of fractured rock mass

the intact coal was used to obtain the specimens of fractured rock mass through earlier loading

and the point cloud dates which represent the distribution of 3-D cracks could be got after CT scanning on fractured rock mass samples and model rebuilding.Lastly

the uniaxial compressive strength of fractured rock mass after scanning was tested and the relation between the index of quantitative description and strength parameter was analyzed.The results showed that the point cloud which was got after CT scanning could represent the distribution status of 3-D cracks in rock mass well.The 3-D cracks in rock mass

a kind of nature fractal

was self-similar

and it’s fractal dimension could be as a index of quantitative description for fracture rock mass.The relation between the quantitative description index (fractal dimension) and the uniaxial compression strength of fractured rock mass was a logarithmic relation in the statistical sense

and the trend of strength parameter decreased with the increase of the complexity of rock mass.