Abstract: Natural gas hydrate deposits, as a new type of green energy, have attracted global attention for broadly commercial exploitable prospect. Methane hydrate (MH) has different formations in the pore of methane hydrate-bearing sediment (MHBS), i.e. pore-filling, cementation, and so on. A pore-filling type MHBS with a specific MH saturation is firstly generated based on the hydrate morphology. Subsequently, a series of consolidated-drained true triaxial tests with a constant mean effective stress is carried out using the distinct element method (DEM) under the same π-plane with different intermediate stress ratios (i.e., b = 0, 0.25, 0.50, 0.75, 1.00). The influence of intermediate principal stress on the macro-micro mechanical properties of MHBS is analyzed by linking the evolution of micro-mechanical parameters (i.e. the contact fabric and the percentage of sliding contact) to the macro-scale behavior of granular material. The results show that there is a good correlation between the strong fabric changes (i.e. major, intermediate, and minor principal fabrics) and the variations in principal stresses (i.e. major, intermediate and minor principal stresses) and principal strains (i.e. major, intermediate, and minor principal strains). The three-dimensional strength of MHBS can be approximately described by Lade-Duncan failure criterion. The percentage of sliding contact increases with increasing intermediate principal stress ratio and reaches the maximum when MHBS is in the triaxial extension state.

Key words: distinct element method, pore-filling type MHBS, consolidated-drained true triaxial test, intermediate principal stress ratio