不同温-压条件下含水合物沉积物的损伤本构关系

环境温度和孔隙压力对含水合物沉积物的力学特性存在重要影响，深刻揭示温度和孔隙压力对含水合物沉积物力学特性的影响机制并对其进行有效地模拟是含水合物地层稳定性评估的前提。在分析温度和孔隙压力变化对含水合物沉积物的力学特性影响机制的基础上，引入温压条件参数来考虑温度和孔隙压力变化对含水合物沉积物力学特性的影响，建立了考虑温度和孔隙压力影响的损伤本构模型。模型假设含水合物沉积物微元强度服从Weibull分布，采用Drucker-Prager强度准则描述微元强度，建立了损伤因子的演化规律。此外，还提供了一套模型参数的确定方法。通过一系列不同温度压力条件下的含水合物沉积物的三轴压缩试验结果对模型进行校核和验证，结果表明，该模型能很好地模拟含水合物沉积物的应力-应变关系，并且能较好地考虑水合物含量、环境温度和孔隙压力对含水合物沉积物的力学特性的影响。

Damage constitutive model for hydrate-bearing sediment under different temperature and pore pressure conditions

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.