Abstract: Delineation of structural homogeneity of rock masses is the basis of statistics and modeling of discontinuities. In practice, an objective partition result is easier to obtain with key factors as indicators and optimal delineation as the final judgment criterion. In order to better characterize the discontinuities in Chinese high-level nuclear waste disposal preselected region in Gansu Beishan, the measure window truncation, sampling bias and grid variability correction are carried out to deal with the discontinuities of rock masses. Such programming realizes structural homogeneity delineation by using a variety of methods and has a preliminary probe into the distinguish capability, applicability and limitation in Beishan. The results show that, as far as the Beishan preselected area be concerned, different delineation schemes are obtained in which the applicability of the correlation coefficient method and the Mahtab’s method are weak in applicability while the Miller’s method is the best and the Miller’s method is increasing sequentially. It is worth mentioning specially that in the Miller’s methods, the 34-block scheme receives the most satisfactory result. At last, the optimal method is applied to Jijicao area; and the delineation result provides a useful direction for the structural network modeling and the following seepage flow path calculations.

Key words: rock mass structure, structural homogeneity delineation, distinguish capability, Beishan of Gansu province