Elastic–Plastic Behavior of Hydrate-Bearing Sediments of the South China Sea under Triaxial Cyclic Loading

Abstract

The comprehensive evaluation of the mechanical behavior stability of hydrate reservoirs is critical for ensuring the success of upcoming industrial trial production. However, potential cyclic loading conditions, such as those caused by periodic vibrations from pile foundations, hydraulic fracturing, and similar activities, are often overlooked. In this study, the clay-silty sediment from the South China Sea was remolded and subjected to drained cyclic triaxial experiments under varying saturation levels (0–45%) and effective confining pressures (1–3 MPa). The following conclusions were drawn: the hydrate sediments show a significant elastic–plastic behavior during cyclic loading and unloading, which leads to energy dissipation; their volumetric strain shows volumetric shrinkage during loading and volumetric expansion during unloading; their Poisson’s ratios change with hydrate saturation and the effective confining pressure, with fluctuations in the range of 0.1 to 0.3; and it is also found that the dependence of the elastic modulus of the hydrate sediments on the axial stress exhibited a linear relationship. This study provides valuable data to support the stability analysis of gas hydrate reservoirs.