| Summary: | Massive methane hydrates occur on sediment matrices in nature. Therefore, sediment-based methane hydrate systems play an essential role in the society and hydrate community, including energy resources, global climate changes, and geohazards. However, a fundamental understanding of mechanical properties of methane hydrate–mineral interface systems is largely limited due to insufficient experimental techniques. Herein, by using large-scale molecular simulations, we show that the mechanical properties of methane hydrate–mineral (silica, kaolinite, and Wyoming-type montmorillonite) interface systems are strongly dictated by the chemical components of sedimentary minerals that determine interfacial microstructures between methane hydrates and minerals. The tensile strengths of hydrate–mineral systems are found to decrease following the order of Wyoming-type montmorillonite- > silica- > kaolinite-based methane hydrate systems, all of which show a brittle failure at the interface between methane hydrates and minerals under tension. In contrast, upon compression, methane hydrates decompose into water and methane molecules, resulting from a large strain-induced mechanical instability. In particular, the failure of Wyoming-type montmorillonite-based methane hydrate systems under compression is characterized by a sudden decrease in the compressive stress at a strain of around 0.23, distinguishing it from those of silica- and kaolinite-based methane hydrate systems under compression. Our findings thus provide a molecular insight into the potential mechanisms of mechanical instability of gas hydrate-bearing sediment systems on Earth.
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