During the harvesting of polymetallic nodules on the seabed, the sediment plume due to disturbance on the seabed impacts the benthic ecosystem. A numerical simulation based on the SPH (smooth particle hydrodynamics) method is used to estimate the time and length scale of the plume impact near the seabed during a small-scale harvesting process. The simulation result considerably agrees with the one from the lab-scale water-channel experiment. It is found that, in the sediment plume, the traced sub-plume with iso-surface of lower sediment concentration travels a longer distance, and spends a longer time to achieve the stable state. Moreover, with the increase of the releasing rate of the disturbed sediment, the sub-plume spreads over greater distance, which also needs more time to achieve the stable state.

To enhance the sampling and exploration of the gas hydrate resources and other seafloor mineral resources within the seafloor sediment stratum, a deep-sea stratum drilling robot inspired by the earthworm’s peristaltic movement was developed in this paper. The support anchor unit is a part of this new type of robot. When the robot moves forward, it must rely on the support anchor unit to provide enough supporting force to counteract the various resistance forces on the front body units. In this paper, the maximum anchoring force of the support anchor unit, also known as the pullout force, is determined by theoretical calculation. The soil failure area during the pulling-out was obtained by simulation for visualization. The maximum anchoring force of the unit in the soil of different properties with different speeds was also obtained by tests to verify the theoretical calculations. And the effect of the support plates’ unfolding action on the maximum anchoring force was further analyzed in this research. The test results provide a helpful research basis for subsequent analysis of the robot’s movement pattern in soil and the effect of movement at different speeds.