Abstract: Temperature and pore pressure have significant effects on the mechanical behavior of hydrate-bearing sediment. It is critical to reveal and simulate the mechanical response of hydrate-bearing sediment under different temperatures and pore pressures for evaluating of stability of hydrate-bearing reservoirs. Through analyzing the influence of temperature and pore pressure on mechanical behavior, this paper introduces a new state parameter, referred to as ‘temperature and pore pressure condition parameter’, to describe the influence of temperature and pore pressure on mechanical behavior of hydrate-bearing sediment. Furthermore, a constitutive model is developed in the framework of continuum damage mechanics theory. This model assumes that the strength of micro-element of hydrate-bearing sediment follows the Weibull distribution, and the strength of micro-element can be described from the Drucker-Prager strength criterion. In addition, a parameter calibration method is proposed for the proposed model. The model is checked and validated by a series of triaxial compression test results of hydrate sediments under different temperature and pressure conditions. The comparison between predicated results and experimental data shows that the proposed model has capacity of simulating the stress-strain relationship of hydrate-bearing sediment. Moreover, the proposed model is able to address the influences of temperature and pore pressure on mechanical properties of hydrate-bearing sediments.

Key words: hydrate-bearing sediment, temperature and pore pressure, temperature and pore pressure condition parameter, damage, constitutive model