Void States Perspective for Critical Hydraulic Gradient of Internally Unstable Noncohesive Soils

Kalore, SA and Sivakumar Babu, GL (2022) Void States Perspective for Critical Hydraulic Gradient of Internally Unstable Noncohesive Soils. In: Geotechnique . pp. 1-52.

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Abstract

The critical hydraulic gradient (icr) for internally unstable soils is observed to be significantly less than the icr given by Terzaghi's classical equation. The difference is due to the uneven stress contributions by fine and coarse fractions of internally unstable soils, and thus an empirical stress reduction factor (α) was considered for icr predictions. Internally unstable soils are coarse fraction dominant with a void ratio of fine fraction higher than the void ratio of overall internally unstable soil. The differential stress states lead to washout of the fines from the local voids of the coarse fraction at a hydraulic gradient less than the icr given by the classical equation. This study presents a theoretical approach for predicting α based on the notion of the effective stress of fine fraction within the voids of a coarse fraction equal to zero for internally unstable soils. The comparison of predicted icr based on the proposed approach and experimental observations obtained from literature and current study has demonstrated the validity of the proposed approach. The applicability of the proposed approach is also illustrated for the estimation of a critical hydromechanical envelope.

Item Type:	Journal Article
Publication:	Geotechnique
Publisher:	ICE Publishing
Additional Information:	The copyright for this article belongs to the ICE Publishing.
Keywords:	Void fraction, Classical equation; Coarse fractions; Critical hydraulic gradient; Filter & drain; Fine fraction; Internal erosion; Noncohesive soil; Piping; Suffusion; Voids ratio, Soils
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	20 Jul 2022 12:23
Last Modified:	20 Jul 2022 12:23
URI:	https://eprints.iisc.ac.in/id/eprint/74956

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