CENTRIFUGE TESTS ON THE LIQUEFACTION BEHAVIOR OF IRON ORE CONCENTRATES WITH DIFFERENT MOISTURE CONTENTS AND APPLIED ACCELERATIONS

摘要

Iron ore concentrates (IOCs) are considered as dangerous cargo during shipping since liquefaction may easily occur under dynamic loads and cause marine casualty. To provide further insight into the true liquefaction behaviors in a simulated gravitational field, a series of dynamic centrifuge model tests were conducted for IOCs with different initial moisture contents (MCs) and applied accelerations. The effect of the initial MC on the liquefaction potential was more significant in the centrifugal models than in our previous small scaled models, while the impact of applied acceleration was weaker. The critical MC threshold of the simulated IOC samples was 9 % for liquefaction to occur at all applied acceleration levels, and the larger the applied acceleration the quicker the liquefaction occurred at a given initial MC. Liquefaction occurred through a combination of ore motion and moisture migration, which was illustrated by a systematic analysis of the ore displacements, the increases in the water levels, the distributions of the MC, and the developments of the pore water pressures. All the IOC samples exhibited similar vertical displacement behaviors, but large horizontal displacements were only observed in the liquefied samples. Meanwhile, the moisture tended to migrate downwards in the non-liquefied samples and upwards in the liquefied ones. Additionally, we suggest using IOCs with the simulated particle size and carboxymethyl cellulose sodium aqueous solution in centrifuge tests.