Seepage-induced internal erosion is observed in both artificially engineered fill structures and natural soil deposits. Fine content is of great significance for the fabric of soil. This paper aimed to determine the critical fine contents of natural soil deposits beyond which the internal stability of the mix was distinctly altered and illustrate the internal erodibility from the viewpoint of fabric. To this end, a fixed-wall permeameter capable of accurately detecting the critical hydraulic gradient of erosion initiation and collecting the cumulative eroded soil mass at a constant inflow rate was developed. Silty clay particles and sandy gravel particles extracted from original soil were employed to reconstitute specimens with fine contents ranging from 0 to 100%. Porosity measurement, seepage testing, and direct shear testing were conducted on remolded samples. Companion control specimens were tested under different flow rates to verify the applicability of the experimental device. The results indicate that according to critical fine content, the fabric of the soil samples with different fine contents could be split into coarse-particle-supported structure (CPSS), fine-particle-supported structure (FPSS), and transitional coarse–fine-particle-supported structure (TCFP). The newly developed experimental device provides a feasible methodology to investigate the internal erodibility of natural soil deposits. Different fabrics correspond to disparate shear strengths and distinct erosion characteristics, including the critical hydraulic gradient of erosion initiation, cumulative eroded soil mass, and average hydraulic conductivity. For coarse-particle-supported structure specimens, the coarse particles predominantly govern the mechanical and hydromechanical properties. An increase in fine content within pores formed by coarse particles could increase shear strength and reduce susceptibility to internal erosion. The mechanical and hydromechanical properties of FPSS specimens were basically controlled by fine particles. Coarse particles suspended in a fine matrix could somewhat increase the soil’s shear strength and reduce internal erodibility. TCFP specimens were most vulnerable to internal erosion in terms of minimum critical hydraulic shear stress and maximum cumulative eroded soil mass. It is essential to expand the scope of research to cover the transitional coarse–fine-grain-supported structure instead of remaining limited to the coarse-grain-supported structure.

在人工工程填充结构和天然土壤沉积物中均观察到了由渗流引起的内部侵蚀。精细含量对土壤结构具有重要意义。本文旨在确定天然土壤沉积物的临界细含量，在此范围内，混合物的内部稳定性发生明显变化，并从织物的角度说明其内部易蚀性。为此，开发了一种能够精确检测侵蚀开始的临界水力梯度并以恒定的流入速率收集累积的侵蚀土壤质量的固定壁式渗透仪。从原始土壤中提取的粉质粘土颗粒和沙砾颗粒用于重建标本含量为0％至100％的标本。孔隙率测量，渗透测试，对重塑样品进行直接剪切测试。伴侣对照样品在不同的流速下进行测试，以验证实验装置的适用性。结果表明，根据临界细度，具有不同细度的土壤样品的织物可分为粗颗粒支撑结构（CPSS），细颗粒支撑结构（FPSS）和过渡粗细结构。颗粒支撑结构（TCFP）。新开发的实验设备为研究天然土壤沉积物的内部侵蚀性提供了一种可行的方法。不同的织物对应不同的剪切强度和不同的侵蚀特性，包括侵蚀开始的临界水力梯度，累积的侵蚀土壤质量和平均水力传导率。对于由粗颗粒支撑的结构标本，粗颗粒主要控制机械和流体力学性能。由粗颗粒形成的孔中细含量的增加可以提高剪切强度并降低对内部侵蚀的敏感性。FPSS试样的机械和流体力学性质基本上由细颗粒控制。悬浮在细基质中的粗颗粒可以在某种程度上增加土壤的剪切强度并降低内部侵蚀性。就最小的临界水力剪切应力和最大的累积侵蚀土壤质量而言，TCFP样品最容易遭受内部侵蚀。重要的是要扩大研究范围，以涵盖过渡的粗粒细支撑结构，而不是仅限于粗粒支撑结构。