粗粒土压实特性及颗粒破碎分形特征试验研究

对多个级配不同含水率的粗粒土进行击实试验，研究粗粒土的压实特性和颗粒破碎分形特征。结果表明，粗粒土最大干密度随级配中粗粒含量的增大而增大，当粗粒含量P5=70%时，最大干密度出现最大值；当P5＞70%时，最大干密度又随粗粒含量的增大而减小，粗粒土击实破碎后的粒径分布具有良好的分形特性，破碎分形维数为2.279 0～2.892 2，均大于击实前粗粒土粒度分形维数；相同级配条件下，粗粒土破碎分形维数随含水率的增大而增大，且粗粒含量P5＞50%时，增幅显著；粗粒土破碎分形维数D与破碎率Bg存在良好的线性关系，且击实前后粗粒土粒度分形维数差值能客观表征颗粒破碎的程度；粗粒含量和含水率是影响颗粒破碎率的两个重要因素，但相对于含水率而言，粗粒含量对破碎率的影响更加显著。

Experimental study of compaction characteristics and fractal feature in crushing of coarse-grained soils

Based on compaction test of different gradations and different moisture contents of coarse-grained soils, the compaction characteristics and fractal feature of coarse-grained soils are studied. The results show that the maximum dry density of coarse-grained soils would increase with the increase of coarse grained content in gradation. The maximum dry density reach the maximum value as the coarse grained content is 70%; while it would decrease with the increase of coarse grained content in gradation as the content is more than 70%. The particle size distribution of crushing granular has a good fractal feature. The crushing fractal dimensions are between 2.279 0－2.892 2; higher than that before test. Under the same gradation condition, the crushing fractal dimension of coarse-grained soils increased with moisture content. The increase amplitude is obvious when P5 is larger than 50%. A good linear regression relation exists between crushing fractal dimensions D and broken rate Bg. Difference value of the granularity fractal dimension before and after compaction can show the crushing degree of coarse-grained soils objectively. Coarse grained content and moisture content are two key factors affected on particle breakage; but the influence of coarse grained content is more obvious.