Experimental study on sinkage and breakout forces for soft soil

The current approach for mining of Poly-metallic nodules at a water depth of 6000m uses a tracked vehicle for locomotion on seabed. As the sea bed sediments are very soft clays, it is necessary to study the soil machine interaction characteristics. The extent of sinkage of mining machine in very soft clays is critical as the soil resistances acting on the mining machine depends on the amount of sinkage. The present study aims to determine the bearing capacity and sinkage in very soft clays under various normal loads for shear strength ranging from 1 to 3kPa. Effect of pitch and height of grouser teeth of the tracked vehicle on sinkage is also studied. Determination of breakout forces for mining machine is also important for the safe retrieval of mining machine. The variation in breakout force with sinkage is described in this study. The size effect on sinkage is studied through experiments on plates of varying dimensions.