Abstract: Rock core-discing is a special mechanical behavior of the rockmass under high in-situ stress conditions. Based on the precious field data of deep rock core-discing, figuring out the characteristics, laws of core-discing and the relationship with stress is of great significance to promote the understanding and theoretical development of deep rock mechanics phenomena. Based on the rock core cake formation data from some boreholes in the Jinping Underground Laboratory,which is the deepest in the world, this paper conducts a statistical analysis of the rock corediscing phenomenon, and examines the occurrence conditions of the rock core-discing, the statistical characteristics of the core disk thickness, and the evolution pattern of the rock core-discing with the drilling depth. The results of this investigation show that the rock core-discing phenomenon is likely to occur in the intact rock masses in the higher stress area; the amount of rock core disk generally decreases with the increase of the borehole diameter, and the thickness of the core disk increases as the diameter of the core increases, the ratio of the thickness of the rock disk to the diameter in different diameter boreholes is distributed between 0.2 and 0.25; the thickness of the cake disk and the maximum principal stress satisfy a negative exponential function relationship.

Key words: High Geo-stress, Rock CoreDiscing, Geometric Properties, Distribution Pattern