The culprit turns solid objects into liquid, sinking cargo ships

Solid goods such as crushed or sand ore can suddenly turn into liquid form and submerge cargo ships weighing hundreds of thousands of tons.

Liquefaction phenomenon can make ships tilt on the water surface, leading to shipwrecks.(Photo: Elias Marine.)

Granular goods such as crushed ore and sand cause a series of shipwrecks every year, according to the BBC. On average, 10 solid bulk carriers were lost at sea annually over the past decade. Solid bulk cargo is defined as granular materials poured directly into the cargo compartment of the vessel. They are capable of switching from a solid state to a liquid state during liquefaction. This could become a disaster for cargo ships and crew.

Scientists have discovered the physical nature of liquefaction of granular materials from geotechnical investigations and earthquake techniques. The intense shaking of the ground caused the pressure on groundwater to increase to the extent that it liquefied the soil. Although we understand this phenomenon and have instructions to prevent the phenomenon from happening, the liquefaction process still sinks the ship, leading to the life of the crew.

Solid bulk goods are usually "two-phase" materials, containing water between hard particles. When hard particles collide with each other, friction between them makes the expression material look like a solid despite water. But as the water pressure increases, the impact force between the particles decreases and the hardness of the material decreases. When the friction is annihilated, the expression material is like a liquid despite containing hard particles.

Solid bulk goods piled up on the land next to the harbor can liquefy when loaded onto the ship due to the build-up of water pressure between particles. This is especially likely if goods are transported by conveyor from the ground to the compartment and poured down from a high altitude. The vibration from the ship engine and the impact of waves during the journey can also increase water pressure, leading to the liquefaction of goods.

When bulk cargo is liquefied, it can move or shoot inside the container, making it less stable. Liquefied goods can completely move to one side of the container. If the cargo is hardened and returned to a solid state, it remains in place, causing the ship to be tilted on the water. Goods can continue to liquefy and move further, increasing the angle of inclination.

At some point, the angle of tilt became so large that it allowed water to enter the hull through the lid of the cargo compartment, or the vessel was no longer stable enough to withstand the waves. If the crew does not take measures to prevent cargo movement, the ship is at risk of sinking.

Sensors in the vessel's cargo compartment can monitor the water pressure of hard bulk cargo. Using laser to track the surface of goods also helps determine the position shift. The challenge now is to develop a low-cost, fast-mounted and rugged enough technology to withstand loading and unloading. If we can overcome this challenge, combine data on water pressure and movement of goods with weather information and movement of the ship, we can generate real-time alerts at the time of arrival. liquefaction.

At that time, the crew could apply measures to prevent excessive water pressure in the cargo, such as draining water from the cargo compartment (to reduce water pressure) or changing the route to avoid weather. bad (to reduce swaying motion). If they can't stop the phenomenon, they will at least evacuate the ship.