Characterisation of intermediate mine tailings using the Medusa flat plate dilatometer
Recently, a new fully automated flat plate dilatometer, Medusa DMT, has been introduced to field investigation works. Along with the capability to conduct high-quality and repeatable DMT tests, this device provided an opportunity for a new series of in situ tests designed to estimate in situ horizontal stress. These extensions to the capability of the DMT are particularly valuable in materials with intermediate behaviour, such as mine tailings, where partial drainage effects can significantly impact test outcomes. This paper introduces the new methods available with the Medusa DMT, namely DMT-Whilst Penetrating (DMT-WP) and DMT-Repeated A (DMT-RA), describes a method for screening for intermediate material behaviour and discusses the process used to reduce the partial drainage effects by testing to measure drained or undrained behaviours. The results from the DMT-WP and DMT-RA tests are analysed alongside adjacent CPTu and Vane Shear Tests (VSTs). The findings demonstrate the value of the new Medusa DMT tests in characterising intermediate mine tailings materials, assessing the drainage effects and providing insight in estimation of coefficient of earth pressure at rest, K0.