Modeling the Mechanical Behavior of Methane Hydrate-Bearing Soil Considering the Influences of Temperature and Pore Pressure

Abstract

Temperature and pore pressure have a significant impact on the mechanical behavior of methane hydrate-bearing soil (MHBS). To characterize the mechanical responses of MHBS under different temperatures and pore pressures, an elastoplastic constitutive model is developed within the framework of the critical-state theory. In the proposed model, an additional variable, called the phase state parameter, is introduced to characterize the temperature and pore pressure condition. Meanwhile, the elastic parameter, plastic modulus, and tensile bonding stress are related to the phase state parameter through several empirical formulas. As a consequence, the influences of temperature and pore pressure on the stiffness, strength, and dilatancy of MHBS are addressed by the proposed constitutive model. Through comparing the predicted results and experimental data, the proposed model is demonstrated to have the ability to capture the influences of hydrate saturation, temperature, and pore pressure on the mechanical behavior of MHBS. In addition, the proposed model is used to analyze the response of MHBS to an increase in temperature or a decrease in pore pressure within the hydrate stability boundary. The result shows that the proposed model can reasonably reflect the mechanical behavior of MHBS induced by heating or depressurization procedures within the hydrate stability boundary.