Abstract：A set of prediction method of rock fragmentation is presented. Generally，there are three kinds of methods to predict fragmentation. The first is to predict the fractal number of fragmentation by relating it with fractal dimension number of crack in the rock. The second belongs to geometric method that directly computes the size of fragmentation by searching the possible crossed cracks. The third is by using energy dissipation during rock fracturing，upon which this paper is focused. In fact，fragmentation is a brittle fracture event which can be studied within the frame of damage mechanics. With the increment of compression，fractal distributed cracks cut the intact rock into fragmented bodies and eventually results in a fractal distributed fragmentation system. According to the principle of conversation of energy，a theoretical formula is established，which represents the relationship among fragmentation size，fractal dimension number of fragmentation system，and damage variable. In order to use the formula in engineering，it is simplified to take a form of relating fragmentation size only with damage variable，provided that the fractal dimension number of fragmentation system is given. Because of the characteristics of self-similarity of fragmentation system，the formula of size-damage can be generalized to fragmentation prediction of jointed rock. When predicting fragmentation of jointed rock，the first is to calculate damage variable by joint data measured from rock mass，and the second is to calculate the minimal size of the fragmentation system according to the size-damage formula. Finally，an example of fragmentation prediction of jointed rock in Jinchuan Corp. is given. In addition，a method of setting up damage model suitable for engineering is also presented. The research has significance in predicting the fragmentation in block caving.
