Behavior of Unsaturated Marine Sediments Containing Gas Hydrate

Existence and dissociation of Gas Hydrate changes the physical and mechanical properties of marine sediments in deep water. So seabed soil will have different responses when it is exposed to the external forcing mechanisms. Available saturated soil models are not capable of well predicting the behavior of this type of sediments. Finite Element Code theta-Stock (Gatmiri, 1997) employed in order to model piezocone penetration into the unsaturated soils containing Gas Hydrate. This model takes into account the interaction of different phases of soil while considering temperature changes in a completely coupled manner. The interactive effects of deformations on the temperature and suction distribution in soil skeleton are included in the program via a temperature-dependent formulation of state surfaces of void ratio and degree of saturation. The nonlinear constitutive law is assumed and the mechanical and hydraulic characteristics of porous medium are temperature dependant. The process of piezocone penetration is modeled by means of cavity expansion theory. Results of this study describe the temperature dissipation and mechanical behavior within these kinds of gassy soils with an acceptable accuracy.