Towards better understanding of CPT data on tailings

• Characterization of tailings deposits is associated with significant challenges in tailings dam design and dam safety assessments. One of the challenges is static liquefaction in the deposited tailings and how this has to be addressed in stability assessments. Concerns have led to design concepts that deposited tailings considered susceptible to liquefaction, will liquefy. Facillities should therefore be designed for such post-liquefaction scenario, i.e. fluidized tailings. Existing upstream-constructed tailings dams are seldom built for a design case with post-liquefaction strength in the tailings. Consequently, mining companies must take dam safety-enhancing measures and rapidly conduct major changes in their tailings dam design.At the same time, there are questions and uncertainties in evaluating static liquefaction potential in tailings that must be addressed. The uncertainties are, among others, related to differences between natural sands and tailings. There is a need to address the applicability of today’s evaluation methods on tailings and this paper will describe how a research project at Luleå University of Technology, funded by Boliden, will investigate and address the uncertainties in the evaluation. Cone Penetration Testing (CPT) in a calibration chamber will be undertaken in the project. A new calibration chamber for CPT is developed, where silty-sandy tailings material will be tested in a controlled laboratory environment. Combined with other laboratory test results, the CPT calibration chamber results will be used to derive new and update existing correlations between CPT data and tailings properties. The research will focus on the mechanical properties of tailings and its influence on the soil behavior around the penetrating cone. This paper will highlight uncertainties in state interpretation from CPT in tailings, present the design work of the calibration chamber and the expectations for the outcome of the CPT calibration chamber research.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Geoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Geotechnical Engineering (hsv//eng)

Nyckelord

Geoteknik

Soil Mechanics

Publikations- och innehållstyp

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