Investigation of full scale track–seabed shear interaction: the saturated soft clay traction model for deep–sea mining vehicle mobility

Tracked deep–sea mining vehicles frequently suffer from excessive slippage and sinkage on soft seabeds, which compromises their operational mobility. Conventional terramechanics models, rooted in terrestrial soil behavior, fail to capture the profound effects of shear softening and strain rate dependence in deep–sea sediments. This study overcomes this limitation by employing a validated numerical model that integrates the coupled Eulerian–Lagrangian (CEL) method with a modified constitutive model. Our investigation systematically decouples the complex interplay between track and seabed parameters, revealing distinct governing mechanisms: steady–state slip is governed by force equilibrium, whereas peak thrust is dominated by acceleration-induced strain rate hardening–a critical finding for throttle control. On the basis of recalibrating the classical Bekker–Wong framework with numerical results, a saturated soft clay traction (SSCT) model that accounts for the characteristics of deep-sea sediments is proposed. This modified empirical model explicitly incorporates seabed–specific softening and strain rate dependent effects. Compared with its traditional counterpart, the SSCT model demonstrates superior predictive accuracy, providing a refined and practical tool for the design and performance forecasting of deep–sea mining vehicle tracks.