干湿循环对土体级配分形特性影响分析

为分析粗粒土受水体干湿循环作用时颗粒级配演化规律,采用颗粒筛分试验统计干湿循环作用后土体颗粒粒径分布,引入颗粒质量-粒径分形模型计算粒径分形曲线(GFC)及分形维数(D),揭示了D随围压及干湿循环次数变化的规律,量化了干湿循环作用对粗粒土D的影响,并建立了计算方程。结果表明,等效替代缩尺法对GFC及D影响较小;制样及筛分过程导致D增大0.63%,室内试验方法引起粗粒土颗粒破碎效应不可忽略。低围压条件下(围压小于0.60MPa),D随围压增大及干湿循环次数增多而增大,剪切作用及水体干湿循环作用加剧了粗粒土颗粒破碎效应。所建粗粒土D计算模型为评价干湿循环对涉水工程填筑土体级配劣化效应提供了依据。

Analysis on Effect of Dry-wetting Cycle on Fractal Characteristics of Particle Gradation

In order to analyze the evolution law of particle size distribution of coarse-grained soil under water dry-wetting cycle, sieving test was used to calculate the particle size distribution of soil after dry-wetting cycling. Granular fractal curve (GFC) and fractal dimension (D) were calculated by introducing particle mass-particle size fractal model. So, the variation of D with confining pressure and the number of dry-wetting cycles was revealed. And then the cycling effect on coarse-grained soil was quantified and its calculation equation was established. The results show that equivalent substitution scale method has little influence on GFC and D. But D increases by 0.63% due to sample preparation and screening. The effect of crushing coarse-grained soil particles caused by laboratory test methods cannot be ignored. Under low confining pressure(less than 0.60 MPa), D increases with the increase of confining pressure and the number of dry-wetting cycles, and the effect of shearing and water dry-wetting cycles on particle breakage of coarse-grained soil is aggravated. The D calculation model of coarse-grained soil provides a basis for evaluating the deterioration effect of dry-wetting cycle on filling soil gradation in water-related projects.