基于损伤能量耗散的岩体块度分布预测

FRAGMENTATION DISTRIBUTION PREDICTION OF ROCK BASED ON DAMAGE ENERGY DISSIPATION

提出一整套岩体块度分布预测方法。首先,根据岩石分形断裂切割岩块的块度形成机制,利用能量守恒关系,建立损伤–能量–碎块尺寸理论关系式。为方便应用,将该式简化。然后,根据块度分布的自相似性,将岩石块度分布特性应用于岩体块度分布预测。提出适合工程应用的损伤模型建立方法,并针对岩体块度分布的特点,定义岩体裂隙损伤参数。作为实例,计算金川节理岩体的块度分布。该研究对于自然崩落法采矿岩体块度分布预测具有重要意义。

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.