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Improvement in the Recovery of Undisturbed Samples in Soils with High Resistance to Penetration Using the Pitcher Sampler

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The reliability of the results of laboratory tests on soil samples to obtain geotechnical parameters is influenced by several processes, ranging from the methodology for collecting, storing and transporting samples to laboratory tests. When obtaining samples, especially when collecting so-called undisturbed samples, the researcher must ensure that the material preserves as much of its in-situ characteristics as possible during this process. The Denison sampler is widely used in geotechnical engineering, but practice in the Brazilian mining industry has shown that this type of sampler does not always recover the expected amount of sample, especially in materials that have high resistance to penetration and granular soils, such as residual soils and compacted dam embankments. The low amount of sample recovered in a Denison sampler is insufficient to carry out all the necessary laboratory tests to guarantee good reliability in the geotechnical parameters used in projects. This can lead to an interpretation of the security of the structure based only on parameter correlations. During a geological-geotechnical investigation campaign in an iron ore tailings storage dam, several sampling attempts were made using a Denison sampler, but low soil recovery was obtained in almost all specimens. Thus, researchers investigated other types of samplers that could increase recovery and improve sampling quality, and also enable the collection of undisturbed samples at depth. The sampler used for this attempt at improvement was the Pitcher sampler type, which despite being available on the market is little known by designers and mining consultants, and consequently is seldom used in investigation campaigns. This study presents the main differences between the Denison sampler and the Pitcher; discusses the operational needs and limitations for the use of the Pitcher sampler; and reports on the successful result of using this sampler in the collection of undisturbed samples from the embankment and the foundation of the inactive mining dam inserted in the Iron Quadrangle of Brazil. This enabled the execution of laboratory tests to obtain the parameters to be used during the elaboration of the projects of the referred structure.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86836

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/