Isotropic compression behavior for methane hydrate-bearing soil with varying temperature and pore pressure

Abstract

Hydrate exploitation may trigger large-scale seafloor subsidence, especially when the depressurization method is used. The isotropic compression characteristics for methane hydrate-bearing soil (MHBS) need to be investigated to evaluate this deformation failure. Change in temperature and pore pressure (TP) condition can generate a considerable influence on the mechanical deformation and strength of MHBS. However, few studies focus on the isotropic compression deformation of MHBS. This paper carried out a series of isotropic compression tests on MHBS with different hydrate saturations and TP conditions. Experimental results show that the MHBS specimens exhibit a completely different isotropic compression curve at different hydrate saturations and TP conditions. The compressibility of MHBS is reduced remarkably with increased hydrate saturation, raised pore pressure, and decreased temperature. Hydrate saturation does not affect the compression index, but it explicitly reduces the swelling index. The yield stress is also enhanced with increasing hydrate saturation. The compression index of MHBS is independent of TP condition, while the swelling index is weakened and the yield stress is enhanced as temperature decreases and/or pore pressure increases. Through employing the phase state parameter as an indicator for TP condition, the influence of TP condition on the isotropic compression characteristics of MHBS is analyzed. Besides, the isotropic compression mechanism of MHBS at different hydrate saturation and TP condition is illustrated.