Permeability evolution directly determine gas production and its efficiency of gas hydrates in the South China Sea. Due to existence of submarine overlying rocks and change of soil internal mechanics during the hydrate exploitation, permeability evolution is significantly affected. Therefore, in this paper, influence of effective stress on the porosity and permeability of sediment with different hydrate saturation was studied, and functional relationship between them was revealed. Effect of cyclic loading and unloading stress on the permeability recovery and damage degree was also discussed. The results show that when hydrate saturation increases, the relation of permeability and effective stress are power function rules, while porosity and effective stress are exponential function rules in clayey sediments. An empirical prediction equation for gas permeability of clay sediments with effective stress was presented, which takes into account hydrate saturation and porosity. In addition, during cyclic loading experiments, the results showed a linear increase in permeability during unloading. The permeability recovery rate and permeability damage rate are completely opposite with change of hydrate saturation. Permeability damage rate of kaolin is different from that of other two kinds of sediment. With the increase of cycle times, the proportion of plastic deformation of sediment decreases gradually.

中文翻译：

---

有效应力和循环荷载对甲烷水合物粘土沉积物渗透率影响的实验研究

渗透率演化直接决定南海天然气水合物的产气量及其效率。由于水合物开采过程中海底上覆岩石的存在以及土壤内部力学的变化，渗透率演化受到显着影响。因此，本文研究了有效应力对不同水合物饱和度沉积物孔隙度和渗透率的影响，揭示了它们之间的函数关系。还讨论了循环加卸载应力对渗透率恢复和损伤程度的影响。结果表明，当水合物饱和度增加时，粘土质沉积物渗透率与有效应力呈幂函数关系，而孔隙度与有效应力呈指数函数关系。提出了考虑了水合物饱和度和孔隙度的具有有效应力的粘土沉积物气体渗透率的经验预测方程。此外，在循环加载实验中，结果显示卸载过程中渗透率呈线性增加。渗透率恢复率和渗透率损害率与水合物饱和度的变化完全相反。高岭土的渗透损害率与其他两种沉积物不同。随着循环次数的增加，沉积物塑性变形的比例逐渐减小。