Use of the Light Weight Deflectometer (LWD) at Highland Valley Copper Mine

Neil K. Singh, Carlos Mejia, Tracy Martison, Farhat Shah, Chris Fleming, Joseph Fitzpatrick

In the proceedings of: GEO2010 Calgary: 63rd Canadian Geotechnical Conference & 6th Canadian Permafrost Conference

Session: W1-A

ABSTRACT: The Light Weight Deflectometer (LWD) is a hand portable version of the falling weight deflectometer typically used for paved road evaluations. It is currently underutilized in North America, although it is gaining acceptance by several American state Departments of Transportation for compaction Quality Assurance. The LWD provides a measurement of the dynamic modulus of elasticity of the soil that is comparable with the static modulus of elasticity determined with the Static Plate Bearing Test. Since early 2008, this equipment has been used at the Highland Valley Copper mine site (HVC) for compaction quality control/assurance of coarse grained aggregate foundations, road bases and earth dam fill materials. In some cases, the LWD was used in conjunction with Nuclear Densometer testing to assess the relationship between in situ dry density and the dynamic modulus of elasticity. This paper includes a discussion on this potential relationship. This paper describes the use of the LWD at the L-L Tailings Dam, the ore stockpile cover foundations, fuel tank station, and at the multiplate overpass foundations and backfill. A comparison of the LWD capabilities with alternative field testing measures is presented along with an evaluation of its effectiveness at HVC.

RÉSUMÉ: Le déflectomètre à faible masse (LWD), version portative du déflectomètre à masse tombante (FWD) est utilisé typiquement pour l'évaluation de chaussées flexibles. Présentement, le LWD, qui procure une bonne évaluation de la compaction faite sur le terrain, est surtout utilisé en Amérique du Nord, mais devient de plus en plus une référence pour le Département des Transports des États-Unis. Plus précisément, le LWD permet de mesurer le module d'élasticité dynamique d'un sol.

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