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对于煤岩体冲击倾向性的评价,目前主要采用煤的冲击能量指数K E,弹性能量指数W ET和动态破坏时间D t三种指标。由于煤岩体的孔隙越发育(也就是孔隙率大、孔隙数量多、结构复杂等),则一般情况下其宏观力学强度就越低,岩体内积聚的能量容易通过塑性变形或破裂消耗掉,冲击倾向性就越低;同时,通过研究煤岩扫描电镜(SEM)图像,计算其孔隙特征参数和分形维数,发现煤岩体具有良好的分形特征,并且孔隙发育程度可以很好地被分形维数所描述,因此引入分形维数D f来描述煤岩冲击倾向性是合适的,一般来说分形维数越大则冲击倾向性越小。
For the evaluation of the impact propensity of coal and rock mass, the impact energy index of coal K E, elastic energy index W ET and dynamic destructive time D t are mainly used at present. As the porosity of coal and rock body grows (that is, the porosity is large, the number of pores is large and the structure is complex), the macro-mechanical strength is generally lower and the energy accumulated in the rock mass is easily consumed by plastic deformation or rupture , The impact propensity is lower. At the same time, through the study of coal and rock scanning electron microscope (SEM) images, the pore parameters and fractal dimension are calculated, and the coal and rock mass have good fractal characteristics and the degree of pore development can be well Therefore, it is appropriate to introduce fractal dimension D f to describe the impact propensity of coal and rock. Generally speaking, the fractal dimension is larger and the impact tendency is smaller.