Abstract: A large number of underground rock discontinuity data can be collected by borehole camera technology. The in-depth analysis of these data will help to further reveal the spatial distribution regularities and geometrical relations of discontinuities. In view of the particularity of geometric parameters from discontinuities obtained in borehole, a new method called feature point which includes the angle, inclination and depth parameters is proposed. The paper mainly focuses on description and calculation process of feature point under the local and global coordinates. The conversion formula between the geometry parameters and feature point coordinates is derived. Distribution regulation of feature points under spatial coordinate system is discussed. The results show that: (1) The feature point is a comprehensive reflection of geometric parameters of discontinuity and spatial location. (2) The distribution of the feature points in space reflects the spatial association relationship of discontinuities. This study provides a new idea and analysis method for the statistical analysis of discontinuities; and helps to research on the discontinuities distribution regularity and intersection relationship, on the development of borehole camera technology and on the basis of the discontinuity geometry characteristics of rock mass stability evaluation with a positive role.

Key words: borehole camera, discontinuities in underground rock, discontinuity feature point, rock mass stability