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Summary: The depressurization method can significantly increase the effective stress in hydrate-bearing reservoirs. Drained triaxial shear tests were conducted on hydrate-bearing sediments with various hydrate saturations at confining pressures up to 20 MPa. The results showed that particle crushing occurred during shearing under high pressures, and hydrate saturation did not have a significant effect on particle breakage. Increasing the confining pressure transformed the stress-strain curves of the specimens from strain-softening to strain-hardening, with a decrease in peak stress ratio and internal friction angle and an increase in cohesion. The critical state line in e-In p' space intersected with the normal consolidation line and moved upward and rotated clockwise with increasing hydrate saturation.
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Lei Wang et al.
Summary: Research has shown that in fine-grained sediments in the South China Sea, the failure strength of methane hydrate-bearing sediments increases with the increase in hydrate saturation and initial effective mean stress. Additionally, the excess pore-water pressure of methane hydrate-bearing sediments remains positive during shear. It is observed that as the hydrate saturation increases, cohesion in the Mohr-Coulomb model increases while the internal friction angle has little dependence on the hydrate saturation.
CANADIAN GEOTECHNICAL JOURNAL
(2021)
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Yanghui Li et al.
Summary: Methane hydrate is being widely considered as an energy source due to its environmentally friendly nature and large reserves, but it may induce geological disasters during the exploitation process, so it is necessary to comprehensively study its mechanical characteristics before commencing commercial development. The study found that under different effective confining pressures, there were differences in the results of multistage and single-stage triaxial loading tests, and the elastic modulus obtained also varied.
Article
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Shi Shen et al.
Summary: Experimental data from mechanical experiments on HBSs at different temperatures and effective confining pressures revealed a significant correlation between the samples' mechanical properties and temperature and effective confining pressure. The strength of HBSs was found to be positively correlated with effective confining pressure and negatively correlated with temperature. Furthermore, the stress-strain behaviors of the samples shifted from hardening to softening with decreasing effective confining pressure and temperature.
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Summary: Triaxial tests were conducted on water-saturated gas hydrate-bearing fine-grained samples from the South China Sea, revealing that the strength and deformation properties were dependent on effective confining stress and hydrate saturation, with a greater influence of hydrate saturation on gas-saturated samples compared to water-saturated samples. Drainage conditions and boundary conditions played critical roles in determining the strength and deformation characteristics of the hydrate-bearing fine-grained deposits.
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Jongchan Kim et al.
Summary: This study investigates the coefficient of earth pressure at rest K-0 in tetrahydrofuran hydrate-bearing sands, revealing that it is mainly governed by hydrate cementation at low stress and by soil particle skeleton at high stress. Estimations of K-0 based on the Poisson's ratio fail to recognize plastic deformation and decementation due to loading.
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Peng Wu et al.
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