Abstract: Marine sandy sediments containing pore-filling type methane hydrate particles can be considered as a class of special granular materials which present apparent discontinuity characteristics. In order to investigate the mechanical characteristics of methane hydrate-bearing sediment (MHBS), the paper preliminarily explores the simulation method about the load mode of methane hydrate under the different temperatures and confining pressures. To numerically simulate such materials, the distinct element method (DEM) can be used by modeling methane hydrate particles as groups of spheres cemented together and filled into the pores of soil skeleton. The back pressure is converted into inter-particle cementation, and it is rational to choose appropriate parameters of inter-particle bond model to realize the role of back pressure. The macro-micro parameter relation among macro-strength, macro-stiffness parameters, microscopic cementation strength and stiffness parameters of parallel bond model is established, based on existing indoor triaxial compression test of methane hydrate. The cementation parameters of parallel bond are determined under the condition of a given temperature and pressure state. The deviator stress obtained from the stress-strain behavior of methane hydrate uniaxial tests in DEM simulation is in line with that of the laboratory triaxial compressional tests. The relationship between macro-micro parameters can be used to realize the simulation about the load mode of methane hydrate by DEM. This study lays foundation to further propose a technique for generating pore-filling methane hydrate-bearing sediments and to study the mechanics and deformation characteristics of MHBS.

Key words: methane hydrate, distinct element method (DEM), parameters inversion, bond model, uniaxial compression test, triaxial compression test