对伊江上游其培水电站大坝垫层料进行4组高围压大型三轴试验,依据试验前后粒径分布资料,通过建立分形模型,研究堆石料的破碎分形特性。结果表明,试验所用的2种堆石料在颗粒破碎后的粒径分布均有良好的分形特性,破碎分形维数为2.6127~2.7232,垫层料下包线的破碎分形维数明显小于垫层料平均线。相同的密度下,随着围压的增加,堆石料破碎分形维数增大,且增大的趋势具有阶段性:当围压较低时,破碎分形维数变化较小;围压升高时,颗粒破碎率增加,破碎分形维数上升的幅度加大。在相同的围压下,破碎分形维数随着密度的增加而增大。破碎分形维数反映了颗粒破碎后粒径的大小,分布的均匀程度,分形维数越大,破碎量越大,并与Marsal颗粒破碎率存在较为显著的线性回归关系。
Four groups of triaxial test with high confining pressure on Qipei hydropower station bedding material are carried out. Based on the test results of particle size distributions,the fractal model is established,and its fractal behavior in crushing is studied. The results show that particle size distributions after particle breakage of these two kinds of rockfills possess good fractal behavior;fractal dimensions vary from 2.612 7 to 2.723 2;and the fractal dimensions of bedding material after crushing are less than those of average line. The fractal dimensions increase with the increasing confining pressure in the same density. The increasing trend has stage characteristics:its growth rate keeps slow under low confining pressure;while the grain breakage increases with confining pressure, its growth rate becomes sharp under low confining pressure. The fractal dimensions increase with the density under the same confining pressure. The magnitude of fractal crushing dimensions reflects the particle sizes of breakage and the uniformity of the particle size distributions. The larger the fractal dimension is,the more the quantity of particle breakage is. Besides,there is a close relationship between fractal dimension and Marsal index of particle breakage.