The effects of fines on the hydraulic properties of well graded materials

The maritime transportation of iron ore and other metallic ores has been of increasing concern as in recent years, several bulk carriers, their cargo and around 200 lives have been lost but the mechanics behind the liquefaction of the cargo is still not well understood. These cargoes are transported at relatively low densities below a certain Transportable Moisture Limit (TML) as specified in the International Maritime Solid Bulk Cargoes (IMSBC) standards to ensure that the ore’s degree of saturation is less than 70%. Studies are currently investigating the cyclic unsaturated soil behaviour and the moisture movements that occur during liquefaction of moist ores that can be caused by wave rocking motions during maritime transportation. Determining the hydraulic properties is necessary in developing a constitutive model that captures the hydro-mechanical response of these materials when subjected to unsaturated cyclic loading conditions. The hydraulic properties, including the permeabilities and soil water characteristic curves (SWCCs), of materials similar in grading to the ores, containing a range of particle sizes less than 9.5 mm and fines (<75 휇m) contents of 18%, 28% and 60% will be presented and the implications of the measured properties on the likelihood of cargo liquefaction will be discussed.