Numeric Simulation for the Seabed Deformation in the Process of Gas Hydrate Dissociated by Depressurization

When the gas hydrates dissociate, the mechanical properties of sediments will change, which may cause the deformation of the seabed. Such incidence will directly affect the stability of the undersea device. Under the consideration of seepage-stress coupling, this paper analyzed the deformation of seabed using finite element method. Duncan Chang’s E-B constitutive model code was written, the impact of stress on the elastic constants was considered in this model. It was implemented in ABAQUS and used to simulating the nonlinear deformation of sediments. The results show that vertical effective stress of soil around the well increase significantly when gas hydrates are exploited by depressurization. The deformation of seabed increases nonlinearly with the increasing of the decomposition radius of hydrate. The maximum settlement reaches 9 m and the maximum horizontal displacement reaches 4 m. The results provide guidance on the submarine construction in the process of gas production from hydrates.