In deep-sea mining engineering, the compression–shear coupling effect of the sediment on the moving tracked mining vehicle must be considered, since it is proved to be existing in compression–shear creep test of the sediment simulant. Based on the endochronic theory, the compression–shear coupling rheological model is established by the definition of intrinsic time and calculation of deviatoric tensor, where the coupling rheological parameters can be obtained by the compression–shear creep test. For simulating sinkage and traction force of the moving tracked mining vehicle, the compression–shear coupling rheological model as well as compressive rheological model and direct shear rheological model (regardless of coupling rheological effect) is programmed and introduced into RecurDyn software (with only traditional elastic–plastic constitutive model) for comparison. Research results show that the sinkage is the largest, and the traction force is the smallest under the compression–shear coupling rheological model, which could better reflect the worse working situation. The compression–shear coupling rheological model could provide theoretical basis for optimal design and safety assessment of the tracked mining vehicle.

The impact load (equivalent impact height) applied to deep-sea sediment by a walking mining machine was first deduced by the energy conservation principle, and the simulative soil was prepared based on the deep-sea sediment collected from the Pacific C-C mining area. The self-designed impact compressive creep tests of the simulative soil were conducted under different ground stresses and impact heights, in order to determine impact compressive creep parameters using a K-H rheological model. Test results show that the impact compressive creep curves have three similar creep stages (transient creep, unstable creep, and stable creep) to static compressive creep curves, where the transient creep deformation and total deformation at the unstable creep stage decrease with the impact load. Among the three impact compressive creep parameters (K₁, K₂, β) of the simulative soil, K₁ is first increased with impact height and finally fluctuated to a certain stable value, while K₂ and β are approximately linearly increased with impact height. The maximum subsidence of the mining machine under a specific designed ground stress and walking velocity predicted by the impact compressive creep constitutive equation can be used for safety assessment of the mining machine.

Based on compressive and shearing rheological models of the deep-sea sediment simulant, new rheological calculation formulae of traction forces for actual track shoe structures were deduced and the multi-objective structural optimization models were established in order to determine optimal track shoe structural parameters. RecurDyn software with introduction of programed rheological models was used to simulate the moving performances of the tracked mining vehicle before and after optimization. Research results show that the maximum traction force calculated by the new rheological calculation formula is much smaller than that by the Bekker theory and more close to the actual situation. The optimized tracked mining vehicle has larger traction force and smaller sinkage than the original tracked mining vehicle, which verifies the validity of the multi-objective optimization model based on the new rheological calculation formula of track force. It is better to choose the thick-triangle track shoe or the sharp-triangle track shoe when the sinkage or the traction force is considered as a dominant factor, respectively. The new rheological calculation formula of traction force and the multi-objective structural optimization model could provide a theoretical basis for safe operation and optimal design of a tracked mining vehicle.