1. School of Mechanics & Civil Engineering,China University of Mining & Technology (Beijing),Beijing　 100083,China; 2. State Key Laboratory for Geo-mechanics and Deep Underground Engineering,Beijing　 100083,China

根据盒维数的计算原理,提出了爆炸载荷下爆生裂纹分形维数的计算方法,并建立了分形维数与爆破损伤度之间的对应关系。利用Matlab软件编写了基于数字图像的爆生裂纹盒维数算法。利用该算法对普通药包和切缝药包两种爆破方式下爆生裂纹的分形特征进行了分析,确定了炮孔周围不同区域的损伤度。结果表明,在普通药包爆破中,随着爆生裂纹的扩展,爆破引起介质的损伤逐渐降低,在炮孔相同距离处,介质的爆破损伤度基本一致。在切缝药包爆破中,爆破介质的损伤度有区域性和方向性特征,在爆生裂纹I区,沿切缝方向产生的爆破损伤较普通药包爆破时相应区域的损伤程度略有降低,且切缝方向的损伤度下降更为显著;对于爆生裂纹II区,沿切缝方向产生的爆破损伤高于普通药包爆破时相应区域的损伤度,而非切缝方向的爆破损伤有明显下降;对于爆生裂纹III区,沿切缝方向产生的爆破损伤明显增加,相应非切缝方向产生的爆破损伤显著降低。基于分形维数的爆破损伤度计算,可用于定量评价爆生裂纹的空间分布特征,为研究岩石爆破损伤的演化规律提供了一条新的途经。

Based on the calculation theory of box-counting dimension,a calculation method to calculate the fractal di- mension of blast-induced cracks is proposed,and the relationship between fractal dimension and damage degree by blasting is established. A box-counting dimension algorithm based on digital image is compiled using Matlab software. The fractal character of blast-induced cracks under both ordinary charge blasting and slit charge blasting is analyzed u- sing the boxing-counting dimension algorithm,and the damage degree of different regions around borehole is deter- mined. The results show that,in ordinary charge blasting,the damage degree induced by blasting reduced with crack propagation,but almost the same in same regions away from the borehole. In slit charge blasting,the damage degree of blast media presents a significant regional and orientated character,in region I,compared to the ordinary charge blas- ting,the damage degree induced by blasting along the slit direction slightly decreased,which reduced significantly in non-slit direction. In region II,the damage degree induced by blasting along the slit direction increased compared to the same region in ordinary charge blasting,while the damage degree decreased in non-slit direction. In region III,the damage degree along the slit direction increased significantly,while it decreased in non-slit direction. The calculation of damage degree induced by blasting based on fractal dimension can be used to quantitatively evaluate the spatial dis- tribution characteristics of blast-induced cracks,so as to explore a new way to study the evaluation law of damage de- gree induced by rock blasting.

YANG Renshu,XU Peng. Fractal study of media damage under blasting loading[J]. Journal of China Coal Society,2017,42(12):3065-3071.