Abstract: Soft marine soils in southeastern coastal areas of China are widely distributed, with occluded gas bubbles that significantly impact soil compressibility. Finite volume (FV) method helps to develop consistent computation method of seabed dynamic response with fluid simulation, and then wave-seabed interaction can be simulated. Operator splitting technique can significantly enlarge time steps for stability of staggered algorithms, and such algorithms can easily be implemented on open-source FV calculation platform, OpenFOAM, thus they are efficient and versatile. Numerical cases indicate that the proposed staggered algorithm can reasonably reflect dynamic responses of highly saturated gassy soil. The existence of occluded bubbles can hugely lower transient responses and amplitudes of pore pressure of highly saturated gassy soil. Meanwhile, when considering gravity, decrease of saturation degree can lead to phase lag of dynamic pore pressure.

Key words: highly saturated gassy soil, operator splitting technique, staggered solution, finite volume method, OpenFOAM