Discrete element numerical simulation of mechanical properties of methane hydrate-bearing specimen considering deposit angles
Methane hydrate sediment (MHS) distributes under the seabed in different deposit angles according to the bottom simulating reflector (BSR) exhibitions. The mechanical properties of the combined sediment composed of soil and MHS dominate the stability of the slope. In this work, simulation models that consider the deposit angles, the confining pressures, loading velocities and hydrate saturation (Sh), were generated by using the discrete element method, following which the bi-axial compression of these models is simulated. The deformation response behavior of these models is studied systematically under different loading velocities, deposit angle, and hydrate saturation conditions. With increasing deposit angles, the peak strength approximately increased first and then decreased. The peak stress gradually decreases with increasing deposit angles when the hydrate saturation is more than 70% under the condition that the confining pressure is 10 MPa. The peak strength and stiffness of sediments increased with increasing Sh. The confining pressure enhanced the peak strength linearly, and the elastic modulus increased first and then decreased in a parabolic equation. Under different loading velocities conditions, the peak strength linearly increased, and the elastic modulus logarithmically increased with increasing loading velocity.
Keywords: methane hydrate sediment, mechanical properties, deposit angle, compress test, discrete element method