Transporting finer fractions inside the soil skeleton or the erosion of base soils within the filter are the two main challenges for earthen hydraulic structures, their foundations, and filter design. Soil particle morphology could influence pore size distribution and transport of fine grains; however, there is not sufficient knowledge on the effect of grain shape on internal erosion. Some experiments designed and conducted in the present study to evaluate the suffusion potential of aggregates with various shapes and different gradations. Particles with six types of grain morphologies and five gradations were collected, and 26 tests were performed. Furthermore, using 3D image processing and visual comparison, particle shape assessed in terms of three features, including sphericity, roundness, and roughness. Results indicated that particle shape influences flow rate, washed-out fine grains in permeameter wall, vertical strain, and mass loss. An increase in the sphericity and roundness causes an increase in the loss of fine grains, pipe in cell sidewall, and vertical strain. Concerning the particle regularity as an indicator of grain morphology, it was demonstrated that the grains with lower regularity are more resistant to suffusion, and thus the resistance to suffusion would decrease with particle regularity. Spherical glass bead and rounded/ medium sphericity specimens were more prone to suffusion at an equivalent or even lower hydraulic gradient than the soil samples with angular/low sphericity grains.

Graphic abstract

中文翻译：

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颗粒形态对无黏性土壤弥漫性的影响

在土骨架内部运输较细的颗粒物或过滤器内基础土壤的侵蚀是土工水力结构，其基础和过滤器设计面临的两个主要挑战。土壤颗粒形态会影响孔径分布和细粒的运输；但是，关于晶粒形状对内部侵蚀的影响的认识不足。在本研究中设计并进行了一些实验，以评估具有各种形状和不同等级的聚集体的富集潜力。收集了具有六种晶粒形态和五个等级的颗粒，并进行了26次测试。此外，使用3D图像处理和视觉比较，可以根据三个特征（包括球形度，圆度和粗糙度）评估颗粒形状。结果表明，颗粒形状会影响流速，渗透仪壁上的细小颗粒，垂直应变和质量损失。球形度和圆度的增加导致细晶粒，电池侧壁中的管道和垂直应变的损失增加。关于作为颗粒形态的指标的粒子规则性，已证明规则性较低的晶粒更耐水凝性，因此抗水凝性随粒子规则性而降低。与具有角/低球形颗粒的土壤样品相比，球形玻璃珠和圆形/中等球形的样品在等效或更低的水力梯度下更易于注水。球形度和圆度的增加导致细晶粒，电池侧壁中的管道和垂直应变的损失增加。关于作为颗粒形态的指标的粒子规则性，已证明规则性较低的晶粒更耐水凝性，因此抗水凝性随粒子规则性而降低。与具有角/低球形颗粒的土壤样品相比，球形玻璃珠和圆形/中等球形的样品在等效或更低的水力梯度下更易于注水。球形度和圆度的增加导致细晶粒，电池侧壁中的管道和垂直应变的损失增加。关于作为颗粒形态的指标的粒子规则性，已证明规则性较低的晶粒更耐水凝性，因此抗水凝性随粒子规则性而降低。与具有角/低球形颗粒的土壤样品相比，球形玻璃珠和圆形/中等球形的样品在等效或更低的水力梯度下更易于注水。因此，抗弥散性会随着颗粒规则性而降低。与具有角/低球形颗粒的土壤样品相比，球形玻璃珠和圆形/中等球形的样品在等效或更低的水力梯度下更易于注水。因此，抗弥散性会随着颗粒规则性而降低。与具有角/低球形颗粒的土壤样品相比，球形玻璃珠和圆形/中等球形的样品在等效或更低的水力梯度下更易于注水。

图形摘要