Abstract: Computerized Tomography (CT) was employed to research the effect of initial damage of soft rock (claystone) and hard rock (marble) on the uniaxial compressive strength. Soft rock samples were damaged in deterioration test area condition; while hard rock was damaged by different sampling methods. There were three test conditions natural test area, wet and dry cycle test area and concrete protection test area. CT scanning results show that the average CT number of soft rock sample is the highest under concrete protection test condition, followed by that in natural test and in wet and dry cycle test conditions. Rock samples with high average CT numbers has correspondingly high uniaxial compressive strength, and vise versa. The CT number of soft rock sample presents certain regularity under different damage conditions. The degree of initial damage of hard rock by using non-destructive sampling is significantly lower than that using conventional sampling method. The compressive strength of hard rock is affected by its initial damage degree, and the CT numbers and uniaxial compressive strength of marble by using non-destructive sampling are higher than those by conventional sampling.

Key words: CT scanning test, initial damage of rock, average CT numbers, uniaxial compressive strength of rock