基于分形理论的堆石料级配设计方法

根据分形理论,推导了堆石料级配的分形分布公式。利用6座心墙坝和5座200 m级面板坝工程的现场级配检测资料进行验证,相关系数基本在0.95以上,吻合较好;相对于不均匀系数Cu和曲率系数C_c指标,粒度分形维数可以更客观地反映堆石料填筑级配平均特性;对英安岩、凝灰岩和混合岩等不同母岩特性的缩尺堆石料进行了室内干密度试验研究,同时结合水布垭等4座大坝原级配堆石料的检测资料,研究了级配(粒度分形维数)与压实干密度的关系,认为级配是影响堆石料压实性能的主要因素;利用粗粒土级配的Cu,C_c与分形维数的关系,首次提出了堆石料、过渡料等大粒径筑坝材料的良好级配范围,其粒度分形维数在2.22~2.63之间。研究结论可为堆石料的级配设计与优化提供依据。

Gradation design method for rockfill materials based on fractal theory

According to the fractal theory, the fractal distribution formula of gradation for rockfill materials is deduced. The field gradation data of six dams with clay core and five 200 m-high CFRDs are used to verify the relevant achievements. The result shows that the correlation coefficient is basically above 0.95. Compared to the uneven coefficient C_u and curvature coefficient C_c, the particle fractal dimension can objectively reflect the average characteristics of rockfill gradation. The relationship between gradation (particle fractal dimension) and density is studied by conducting the extreme dry density tests on scaled rockfill materials of different source rocks from dacite, tuff and migmatite. In combination with the field gradation rockfill data of four dams, including Shuibuya Dam, the conclusion is drawn that the gradation is considered as the main factor affecting the compaction properties of rockfill. By means of the relationship among C_u, C_c and the particle fractal dimension, the favorable gradation scope is deduced for the coarse-grained materials such as the rockfill and transition materials, providing the basis for the gradation design and optimization of rockfill materials.