Abstract: The decomposition of natural gas hydrate generates excess pore pressure, which will lead to the deterioration of the engineering properties of deep-sea energy soil and cause geological disasters such as submarine landslides. Considering the effect of deep-sea energy soil permeability, a modified Grozic-Nixon excess pore pressure model is established. The Storegga submarine landslide, as the research case, is compared with the modified Grozic-Nixon model and Xu-Leonid model, and the research results are analyzed. Based on the modified model, further research is carried out to reveal the time-varying law of excess pore pressure and the effect of different parameters on the excess pore pressure. The results show that the maximum value of excess pore pressure calculated by the modified model reduces by about 21.5% compared with the original model. The excess pore pressure first accumulates and then dissipates, and the accumulation rate gradually decreases, while the dissipation rate first increases and then decreases. The effects of hydrate decomposition rate and deep-sea energy soil permeability on the excess pore pressure have the most significant correlation to excess pore pressure, and the maximum excess pore pressure at selected conditions can differ by 6 times at most.

Key words: deep-sea energy soil, excess pore pressure, permeability, time-varying law, parametric analysis