Study on the Influencing Factors of Sampling Representativeness of Rock Joints

The non-uniformity feature of rock joints' surface profiles is the main influencing factor of the sampling representativeness. In order to analyze the sampling representativeness of rock joints statistically, the joint roughness coefficient (JRC) of 18 pieces of natural slate rock structural plane samples with size from 100mm to 1000mm were measured. The results show that it is necessary to evaluate the representativeness of rock joints in engineering practice due to the large non-uniformity of JRC. The total variation of JRC for different measurement sections, sizes and samples indicates that the sampling representativeness can be evaluated by the average value and the distribution probability of JRC; moreover, the sampling representativeness should be considered the statistical law evaluation of JRC for the concrete size and sample, and offered the accurate standard in changing range.