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Tracked mining vehicles (TMVs) are key equipment in deep-sea mining systems and can easily slip when walking on soft sediments on the seabed. Thus, it is important to investigate the effect of track parameters and grounding-specific pressure on the shear interaction between mining vehicles and sediment. The sediment was simulated using a mixture of bentonite and water, and a shear test of the track with a single grouser and sediment was conducted. A numerical model of the track–sediment shear test was established, and the shear strength and failure mode of the sediment soil under the track action were examined. The results demonstrate that the peak shear strength of the track–sediment interface increases with an increase in the grounding-specific pressure, gradually increases with an increase in grouser height, and tends to stabilize at a given level of grouser height. Owing to the presence of the grouser, the deep-sea sediment transitions from the elastic state to the plastic state faster than the typical clay during the shear test. The variation law of peak shear strength at the track-sediment interface with the height of track grouser under different grounding-specific pressures was analyzed, and a modified shear stress-displacement relationship model was proposed. Wedge failure is the predominant method of failure for a single-grouser shear sediment soil at various heights. The primary factor affecting the horizontal disturbance range is the grouser height, and the range increases as the grouser height increases; the primary element affecting the vertical disturbance range is the grounding-specific pressure, and the range increases as the grounding-specific pressure increases. The relationship of the grouser height and cohesiveness with the interfacial shear strength was examined and a new shear stress–displacement relationship model that can accurately capture the shear mechanical behavior between the track and sediment under various grouser heights was proposed. In conclusion, the study findings could serve as a guide for the engineering design of a TMV walking system. • Explored the characteristics of the shear stress-displacement curves, and analyzed the effects of the grouser height and the grounding specific pressure on the peak shear strength of the interface. • Proposed a shear stress-displacement relationship model considering the grouser parameters. • Analyzed the failure process and final failure mode of sediment from the mesoscopic perspective. [ABSTRACT FROM AUTHOR]

In response to the global demand for commercial mining of deep-sea manganese nodules, the four-tracked mining vehicle (FTMV) with excellent tractive and travelling performance is crucial for constructing the entire commercial system. In order to better evaluate the tractive and travelling performance of the FTMV, the dynamic sinkage phenomenon concerning soft seabed and front-rear track effect are proposed. Meanwhile, the pressure-sinkage and traction force-slip rate mathematical models are established based on terramechanics theory. The quantitative calculation was carried out based on the model and found that the grouser's parameters affect the sinkage depth of the FTMV. In the range of 10 ~ 20 cm, the height of the rectangular grouser increases by 1 cm, which will lead to a 0.15 cm of sinkage depth decreased. When the ratio of rectangular grouser thickness to track shoe length is between 0.1 and 0.3, every 1% increase in this ratio will decrease a 0.13 cm of sinkage depth. The maximum traction force obtained by the FTMV from the soft seabed sediment was 54.5 kN, which occurred when the slip rate of the track was 16%. Moreover, due to the front-rear track effect, the traction force of the front and rear tracks showed a significant difference, the front track contributed 32.4 kN, and the rear track contributed 22.1 kN when the traction force reached the peak. Furthermore, the optimization directions for track parameters were suggested according to the relationship surface of the track dimensional parameters-slip-traction. It was found that each track was 4.2 ~ 6 m long, with a length-width ratio of 3.2, which was conducive to the reduction of track slip and got relatively much traction force from soft seabed sediment. The simulation results confirm dynamic sinkage and front-rear track effect and verify the accuracy of the new traction force-slip rate model, providing a valuable reference for the development of commercial deep-sea mining vehicles. • The dynamic sinkage phenomenon and the front-rear track effects of the four-tracked vehicle are proposed. • The track traction force-slip rate model of the four-tracked seabed mining vehicle was derived. • Quantitative calculations and three groups of computer simulations were conducted to verify the accuracy of the new traction force-slip rate model. [ABSTRACT FROM AUTHOR]