Application and improvement of a stress partition framework-based methane hydrate-bearing sediment constitutive model for wide range confining stress

A constitutive model of methane hydrate-bearing sediment (MHBS) was recently proposed based on a stress partition framework (SPF-MHBS). To capture the mechanical behavior of MHBS under a wide range of effective confining pressures, this study introduces the equivalent granular void ratio (e*) and the particle breakage index (Br) associated with critical state variables into the original SPF-MHBS model. A comprehensive set of triaxial tests on MHBS under 0.2-20 MPa effective confining stress were simulated. The simulation results indicate that based on appropriate parameter calibration, the response of specimens under low effective confining stress can be acceptably represented using the original SPF-MHBS model. However, at high confining stress, the simulated strength of pure sand was overestimated, while that of the hydrate-bearing specimen was and underestimated. Dilatancy was also significantly overestimated at high confining stress. After introducing the e* into the original model, the performance under relatively low pressure is improved and three model parameters are reduced from the original model. After introduction of Br, the model performance is further improved at high confining stress. The improvements allow the SPF-MHBS model to provide a unified description of MHBS behavior under a wide range of confining stress.

Automated summary

This study introduces the equivalent granular void ratio (e*) and the particle breakage index (Br) into the original constitutive model of methane hydrate-bearing sediment (MHBS) based on a stress partition framework (SPF-MHBS) to capture the mechanical behavior of MHBS over a wide range of confining pressures. Simulation results show that the original model can adequately represent the response of specimens under low effective confining stress, but overestimates the strength and dilatancy at high confining stress. After introducing e* and Br, the model performance is improved, allowing for a unified description of MHBS behavior under a wide range of confining stress.