Study on the Pressure–Sinkage Process and Constitutive Model of Deep-Sea Sediment

Abstract

The driving performance of subsea mining vehicles is greatly affected by the pressure–sinkage characteristics of deep-sea sediment. Therefore, it is of great importance to analyze the microscopic properties of deep-sea sediment and establish the corresponding pressure–sinkage model for the safe operation of subsea mining vehicles. Hence, the present paper focuses on the physical properties of deep-sea sediment to provide a preliminary understanding of its pressure–sinkage process and evolution according to the solid–liquid two-phase flow characteristics and particle flow mechanism. In addition, the stress loading time and the rheological theory are applied in order to introduce a four-element model that describes the various pressure–sinkage stages that correspond to each stage of deep-sea sediment evolution. On this basis, the parameters of the pressure–sinkage constitutive model are determined by a specific calculation method. Moreover, a new pressure–sinkage constitutive model of deep-sea sediment that considers the time-variable mechanical properties is established in order to describe the full sinkage process. Finally, research results from the existing literature and experimental data are used to verify the rationality and correctness of the model. The results show that the proposed pressure–sinkage constitutive model is in good agreement with experimental data and is effective in describing the evolution of the mechanical properties and the trend in the sinkage rate of deep-sea sediment at various stages. A comparison with the Kelvin model indicates that the proposed pressure–sinkage constitutive model provides superior accuracy with the use of fewer parameters. Consequently, this study can provide a theoretical basis and technical support for the design of subsea mining vehicles.

A Review on Underwater Collection and Transportation Equipment of Polymetallic Nodules in Deep-Sea Mining

“…Polymetallic nodules, cobalt rich crust, and polymetallic sulphides are the typical marine mineral resources at present. Polymetallic nodules are potato-shaped and widely distributed in 4000-6000 m of deep-sea basin sediment surfaces [5]. Cobalt-rich crust is attached to seamount mountains, ridge tops, and survey surfaces, or exposed bedrock surfaces at 800-2500 m [6].…”