Deformation mechanisms of coexistence type methane hydrate-bearing sands: A particulate-scale investigation

This study aims to explore the effect of cementing ratios λ on the deformation and failure mechanisms from macroscopic and particle scales. First, a new numerical sample preparation technique of coexistence type MH-bearing sands is employed by analyzing the microstructure of coexistence type hydrate-bearing sands. A series of biaxial compression tests are carried out via the discrete element method (DEM), considering cementing ratio λ. The DEM simulation results show that as the cementation ratio λ increases, the inclination of the shear bands of the samples gradually increases, while the thickness of the shear bands gradually decreases. The formation of shear bands is directly related to the breakage events of the bonded contacts S–C and the evolution of the contact fabric of S–C and S–P. The presence of bonded clusters due to the remaining hydrate bonding inside the shear bands contributes to not only the stabilization of larger buckling of the column-like structure but also the formation of large void space. The findings of this study not only offer new insights to the research of deformation and failure mechanisms of MH-bearing sands but also can contribute to the safe exploitation of methane hydrate in future studies.