Paper contribution

Traffic-Light Framework for Early Liquefaction Assessment in Tailings Storage Facilities

Nikolay Y. Milev

Proceedings
EUROCK 2026
Pages
1033-1039
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

This study presents an index-based classification framework for early liquefaction screening and laboratory test prioritization in Tailings Storage Facilities (TSFs), where strong material variability and limited access to advanced testing often constrain detailed analyses. A dataset of 391 tailings samples was evaluated using the Unified Soil Classification System (USCS), and a three-level traffic-light scheme (RED–YELLOW–GREEN) was established to classify materials according to their expected liquefaction behaviour. The RED class comprises sand-like materials that require full liquefaction evaluation and is subdivided into clean sands (R1), silty sands (R2), and low-plasticity silts (R3), reflecting increasing contractiveness, reduced drainage capacity, and lower post-liquefaction residual strength. The YELLOW class includes mixed-fines and borderline materials whose liquefaction susceptibility cannot be determined reliably from index properties alone and therefore requires additional in-situ or laboratory evidence. The GREEN class includes clay-like tailings that are not expected to undergo sand-type liquefaction, although cyclic softening under seismic loading remains possible. A practical procedure is proposed for selecting a minimal number of monotonic and cyclic laboratory tests when project constraints permit only limited advanced testing. Application of the framework shows that one representative silty sand material is sufficient to characterize the cyclic resistance of the dominant sand-like tailings, while low-plasticity silt must still be tested because of its highly contractive response and its disproportionate influence on static liquefaction initiation and post-failure mobility, even where it is not volumetrically dominant. The proposed classification supports preliminary liquefaction hazard zoning, defensible laboratory planning, and early identification of high-risk zones in TSFs.

Contributors

Authors

  1. Nikolay Y. Milev University of Architecture, Civil Engineering and Geodesy (UACEG), Sofia, Bulgaria ORCID 0000-0003-4470-8097

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