DISCRETE ELEMENT SIMULATION OF THE SHEAR BEHAVIOR OF CEMENTED METHANE HYDRATE-BEARING SANDS

The methane hydrate is a new type of clean energy, and is widely distributed in deep sea sediments and permafrost. It is necessary to study the mechanical properties of the methane hydrate-bearing sands. In this paper, a method of generating the discrete element model of cemented methane hydrate-bearing sands is proposed. The model is used to simulate a drained biaxial test. The accuracy of the discrete element model is verified by comparing it with previous experimental data. The macro and micro characteristics of the methane hydrate-bearing sands are then analyzed using the model. The results show that the shear strength, strain softening characteristics and dilatancy of the sand increase with the increase of methane saturation, that the evolution of the hydrate fracture number is closely related to the deviator stress, that the hydrate fracture number increases most rapidly when the deviator stress reaches the peak value, and that the hydrate fracture, particle movement and the porosity change inside and outside the shear band during the test are obviously different. Through the analysis of some micro indexes such as the bond breaking ratio and local porosity inside and outside the shear band, the mechanism of the macro behavior such as the deviator stress and volume change of the methane hydrate-bearing sand is further explained.