Prediction of mechanical characteristics and micro-mechanism analysis of fracture-filling hydrate-bearing sediments

A significant portion of global hydrate reserves is located within clayey-silt marine sediments, primarily in the form of fracture-filling hydrates. The dynamic evolution of these hydrate occurrence states induces considerable alterations in the mechanical properties of the surrounding sediments, which in turn play a crucial role in submarine slope stability, environmental impacts, and engineering safety during resource extraction. Currently, the majority of research has concentrated on pore-filling hydrate reservoirs, while studies on fracture-filling hydrates remain relatively scarce due to experimental limitations. This study utilizes the discrete element method to predict the macroscopic mechanical behavior of fracture-filling hydrate-bearing sediments under varying hydrate occurrence characteristics and to explore the underlying microscopic mechanisms. The results reveal that an increase in the fracture-filling number leads to a higher proportion of tensile breakage in cementation, whereas a larger fracture-filling width enhances the occurrence of shear breakage in cementation. Both increases in width and number result in an increase in the proportion of strong force chains. Furthermore, increased tortuosity causes displacement and velocity changes in sediments near the fractures, resulting in shear slipping within the sediments. This study provides valuable insights into the exploitation of hydrate resources, submarine disaster mitigation, and the reduction of greenhouse gas emissions from hydrate dissociation.