Dynamic coupled thermo-hydro-mechanical problem for heterogeneous deep-sea sediments under vibration of mining vehicle

Due to the influence of deep-sea environment, deep-sea sediments are usually heterogeneous, and their moduli of elasticity and density change as depth changes. Combined with the characteristics of deep-sea sediments, the thermo-hydro-mechanical coupling dynamic response model of heterogeneous saturated porous sediments can be established to study the influence of elastic modulus, density, frequency, and load amplitude changes on the model. Based on the Green-Lindsay generalized thermoelasticity theory and Darcy’s law, the thermo-hydro-mechanical coupled dynamic response model and governing equations of heterogeneous deep-sea sediments with nonlinear elastic modulus and density are established. The analytical solutions of dimensionless vertical displacement, vertical stress, excess pore water pressure, and temperature are obtained by means of normal modal analysis, which are depicted graphically. The results show that the changes of elastic modulus and density have few effects on vertical displacement, vertical stress, and temperature, but have great effects on excess pore water pressure. When the mining machine vibrates, the heterogeneity of deep-sea sediments has great influence on vertical displacement, vertical stress, and excess pore water pressure, but has few effects on temperature. In addition, the vertical displacement, vertical stress, and excess pore water pressure of heterogeneous deep-sea sediments change more gently. The variation trends of physical quantities for heterogeneous and homogeneous deep-sea sediments with frequency and load amplitude are basically the same. The results can provide theoretical guidance for deep-sea mining engineering construction.