Bulk cargo liquefaction incidents during marine transportation and possible causes

During marine transportation, a combination of cyclic loading, fine particles and moisture within a bulk cargo can result in liquefaction causing the bulk carrier to list or capsize. The objective of this study is to investigate incidents where bulk cargoes liquefied during transportation and what resulted from these incidents, including the loss of human life and industry assets. In addition, the effectiveness of determining the Transportable Moisture Limit (TML) using the Modified Proctor/Fagerberg Test (MPFT) for Iron Ore Fines (IOF) is questioned by developing an apparatus used to observe the apparent shear strength of a sample of IOF. Between 1988 and 2016, 23 incidents were reported where liquefaction of a bulk cargo was suspected. These incidents resulted in 138 casualties and the loss of 17 vessels. It was found that incidents are continuing to occur even after the implementation of mandatory testing. Using an apparatus developed for this study, samples of IOF showed a sudden loss of shear strength at moisture contents lower than the TML with indications liquefaction had occurred. Although further testing is required to confirm some assumptions made, the study concluded that the IOF tested was assumed to be liquefiable at the TML determined using the MPFT.