Mechanical Behaviors of Sandy Sediments Bearing Pore-Filling Methane Hydrate under Different Intermediate Principal Stress

Methane hydrates are an attractive source of future clean energy and are abundant in voids of sediments, in permafrost regions, and along continental slopes. Understanding the mechanical behavior of methane hydrate-bearing sediment (MHBS) is essential for commercial gas production from hydrate reservoirs. In this paper, the effects of the intermediate principal stress are studied on the microscopic and macroscopic mechanical behavior of MHBS-filled porous media. Using discrete element method (DEM) simulations, methane hydrates are modeled as cemented agglomerates filling the pores of soil at a specific hydration level. The simulated sample is sheared under strain-controlled conditions to different values of the intermediate principal stress ratio b. The results suggest evolution rules of the principal stresses that depend on the parameter b. The friction angle increases with b, reaching a peak value at a certain value, after which it decreases. Monitoring local variables, including principal strong fabric, contact rose diagram, coordination number, and damage parameter, the effects on the macroscopic bulk behavior are demonstrated. In particular, the changes in the fabric tensor are strongly correlated with response to changes in the principal stresses, the parameter b, and the strain tensor.