Solid bulk cargo liquefaction: numerical investigation and proposal of safety envelopes

Liquefaction of solid bulk cargo during marine transportation is a cause of loss of vessels and life at sea, however limited research has been conducted to understand the mechanism and reduce risks. The work presented in this paper addresses this subject from the soil mechanics perspective through simplified numerical assessment carried out by means of a coupled hydromechanical finite element analysis with an advanced effective stress constitutive model (PM4Sand). Typical responses of solid bulk cargo to dynamic loading are discussed in terms of generation of excess pore pressure and its changes during loading, alongside dissipation and changes in the state of the cargo post-loading. Results of parametric studies are presented and show how various geotechnical characteristics of solid bulk cargo contribute to the risk of liquefaction. The parametric analyses are summarized in a proposed new framework of simplified safety envelopes.