Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations

Internal erosion is a phenomenon in which fine particles are removed by seepage through pore channels between coarse particles in internally unstable soil. It can lead to widespread pavement collapse or sinkholes, undesirable incidents in tunnel engineering and dike foundations, and clogging of oil...

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Main Authors: Marziyeh Salajegheh, Mahmoud Yazdani, Vahid Pachideh
Format: Article
Language:English
Published: Elsevier 2025-03-01
Series:Transportation Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666691X24000733
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author Marziyeh Salajegheh
Mahmoud Yazdani
Vahid Pachideh
author_facet Marziyeh Salajegheh
Mahmoud Yazdani
Vahid Pachideh
author_sort Marziyeh Salajegheh
collection DOAJ
description Internal erosion is a phenomenon in which fine particles are removed by seepage through pore channels between coarse particles in internally unstable soil. It can lead to widespread pavement collapse or sinkholes, undesirable incidents in tunnel engineering and dike foundations, and clogging of oil wells. The erodibility of soil is influenced by critical factors such as the plasticity index (PI) and fines content (FC). However, the combined effects of these factors on internal erosion remains uncertain. For this reason, in this research a triaxial-erosion apparatus was developed to perform an experimental and mathematical investigation of erosion of sand-fines mixtures. Three different clay-sized particle types (rock powder, kaolinite or bentonite) each with three fines contents 20 %, 25 % and 30 % were used. The results indicated that while the output velocity initially rose rapidly with an increasing hydraulic gradient during the early stages of erosion, hydraulic conductivity eventually decreased due to the clogging of particles in specific areas and the blockage of flow paths. The non-Darcy flow behavior resulting from internal erosion positively impacted seepage control in tested soils. Increasing the PI and fines content enhanced the stability of the sample, as PI had a significant impact on the flow in soils with a higher FC. It was seen that rapid erosion was experienced by rock powder mixtures before stabilization, gradual erosion occurred in bentonite due to high cohesion, and uniform erosion was exhibited by kaolinite without significant flocculation. Following erosion, the granulation results of various soil layers clarified three interconnected internal erosion processes: reattachment, rearrangement, and transport. In this study, an equation is derived that describes the variation in the eroded mass with respect to the hydraulic gradient, time, PI and FC.
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spelling doaj-art-b0908830b38145d8a83c1ee9ec36aa7c2025-01-18T05:05:24ZengElsevierTransportation Engineering2666-691X2025-03-0119100299Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigationsMarziyeh Salajegheh0Mahmoud Yazdani1Vahid Pachideh2Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran 14117-13116, IranFaculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran 14117-13116, Iran; Corresponding author.Faculty of Civil and Environmental Engineering, Amirkabir University of Technology, 424 Hafez Ave., Tehran 15875-4413, IranInternal erosion is a phenomenon in which fine particles are removed by seepage through pore channels between coarse particles in internally unstable soil. It can lead to widespread pavement collapse or sinkholes, undesirable incidents in tunnel engineering and dike foundations, and clogging of oil wells. The erodibility of soil is influenced by critical factors such as the plasticity index (PI) and fines content (FC). However, the combined effects of these factors on internal erosion remains uncertain. For this reason, in this research a triaxial-erosion apparatus was developed to perform an experimental and mathematical investigation of erosion of sand-fines mixtures. Three different clay-sized particle types (rock powder, kaolinite or bentonite) each with three fines contents 20 %, 25 % and 30 % were used. The results indicated that while the output velocity initially rose rapidly with an increasing hydraulic gradient during the early stages of erosion, hydraulic conductivity eventually decreased due to the clogging of particles in specific areas and the blockage of flow paths. The non-Darcy flow behavior resulting from internal erosion positively impacted seepage control in tested soils. Increasing the PI and fines content enhanced the stability of the sample, as PI had a significant impact on the flow in soils with a higher FC. It was seen that rapid erosion was experienced by rock powder mixtures before stabilization, gradual erosion occurred in bentonite due to high cohesion, and uniform erosion was exhibited by kaolinite without significant flocculation. Following erosion, the granulation results of various soil layers clarified three interconnected internal erosion processes: reattachment, rearrangement, and transport. In this study, an equation is derived that describes the variation in the eroded mass with respect to the hydraulic gradient, time, PI and FC.http://www.sciencedirect.com/science/article/pii/S2666691X24000733Internal erosionTriaxial testPlastic indexFines contentGap-graded sand
spellingShingle Marziyeh Salajegheh
Mahmoud Yazdani
Vahid Pachideh
Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
Transportation Engineering
Internal erosion
Triaxial test
Plastic index
Fines content
Gap-graded sand
title Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
title_full Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
title_fullStr Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
title_full_unstemmed Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
title_short Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations
title_sort effect of internal erosion on the hydraulic behavior of gap graded coarse fine mixtures experimental and mathematical investigations
topic Internal erosion
Triaxial test
Plastic index
Fines content
Gap-graded sand
url http://www.sciencedirect.com/science/article/pii/S2666691X24000733
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AT vahidpachideh effectofinternalerosiononthehydraulicbehaviorofgapgradedcoarsefinemixturesexperimentalandmathematicalinvestigations