Abstract:Disked core is one of the typical performance of high geostress environment in deep engineering area, and its morphological features can reflect the stress intensity and direction to some extent. Relying on the world's deepest (2 400 m) Jinping underground laboratory, field work was carried out and the disked core of different holes and direction were recorded in detail. Based on blue light no-contact LED scanning technology, coordinate data of rupture surface and side in three dimensions were obtained accurately. Detailed morphology of rupture surface and side of core was reconstructed. The shape of disked core and distribution of small rock step were studied through scanning technology. Studies of different type of disked core and theirs fractal dimension on different directional profiles were done. Combined with the numerical model, the stress in different locations of core residual roots which may result in disked core was learned in depth. The results showed that rupture surface has four morphological types, among which small rock step appears at periphery of the core and the rock shows asymmetric thickness. The position of the maximum fractal dimension is the same as the direction of component part of maximum principal stress. Crack propagation can be divided into two situations. The direction of fissure is divided into radial and axial direction. The first mode of destruction produces the core with asymmetrical thickness. The second mode of destruction produces a lamp-like rupture surface and the phenomenon of small rock step appears on periphery of the section. The first mode showed that crack would propagate along the direction of larger geostress under three unequal geostress. The second explored the reason of disked core under combined effect of rotation of drill and geostress. These results reflected the stress mechanism of disked core which will be useful for distinguishing the cause of disked core and identifying the geostress environment.