DEM simulation of coexistence type methane hydrate bearing sediments

• Published in: Environmental Geotechnics
• Main Authors: Liu, Jun, Jiang, Mingjing
• Format: Article in Journal/Newspaper
• Language: English
• Published: Thomas Telford Ltd. 2023
• Subjects: Methane hydrate
• Online Access: http://dx.doi.org/10.1680/jenge.19.00066; https://www.icevirtuallibrary.com/doi/pdf/10.1680/jenge.19.00066

The hydrate morphology in sandy methane hydrate (MH)-bearing sediment (MHBS) is commonly classified as pore-filling, cementation, grain-coating and load-bearing. This paper presents a numerical investigation into the mechanical behaviour of coexistence-type MHBS using the discrete-element method (DEM). The coexistence type is represented as a combination of pore-filling and cementation types. For MHBS with a given MH saturation (S MH ), the relative content of pore-filling and cementation is characterised by the cement ratio λ (λ = 0 means pure pore-filling and λ = 1 means pure cementation). A series of drained triaxial compression tests is simulated, and micromechanical variables such as bond breakage are examined. The results show that (a) the strength and dilatancy of the coexistence-type MHBS are higher when the cement ratio is larger. The normalised strength and secant modulus increase linearly with the cement ratio. (b) When the cement ratio increases, the critical-state line on the mineral void ratio e cr –ln p′ projection shifts towards a higher position and the bond breakage ratio is larger. (c) The shear stress of the coexistence-type MHBS with cementation is affected by the MH generation process due to the MH bond breakages.