The Failure Mechanism of Methane Hydrate-Bearing Specimen Based on Energy Analysis Using Discrete Element Method

• Published in: Sustainability
• Main Authors: Bin Gong, Ruijie Ye, Ruiqi Zhang, Naser Golsanami, Yujing Jiang, Dingrui Guo, Sajjad Negahban
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: methane hydrate-bearing sediments; composite material; mechanical property; discrete element method; PFC numerical simulation; Environmental effects of industries and plants; TD194-195; Renewable energy sources; TJ807-830; Environmental sciences; GE1-350; Methane hydrate
• Online Access: https://doi.org/10.3390/su15021216; https://doaj.org/article/7cc7fbf5921d45c797a50314df7d090b

Studying the failure mechanism of methane hydrate specimens (MHSs) is of great significance to the exploitation of methane hydrate. Most previous studies have focused on the macro or micromechanical response of MHS under different conditions. However, there are a few studies that have investigated the mechanical response mechanism of MHS based on energy evolution. Therefore, in this study, a numerical model of the methane hydrate-bearing sediments was constructed in the particle flow code (PFC) environment. Then, the numerical model was validated using the conducted laboratory tests; and a series of numerical tests were conducted under different methane hydrate saturation conditions, and the obtained results were analyzed. These results qualitatively describe the main mechanical properties of the methane hydrate-bearing sediments from the viewpoint of energy evolution. The simulation results indicated that during the shear test, the bond breaks at first. Then, the soil particles (sediments) start to roll and rarely slid before shear strength arrives at the highest value. Around the highest shear strength value, more soil particles begin to roll until they occlude with each other. Strain softening is induced by the combined action of the breakage of the hydrate bond and the slipping of soil particles. The higher the hydrate saturation is, the more obvious the strain softening is. Considering that a good agreement was observed between the numerical simulation results and the laboratory test results, it can be concluded that the numerical simulation approach can complement the existing experimental techniques, and also can further clarify the deformation and failure mechanism of various methane hydrate-bearing sediments. The results obtained from the present study will contribute to a better understanding of the mechanical behavior of the gas hydrate-bearing sediments during hydrate dissociation and gas exploitation.