Abstract Safe and economic methane gas production, as well the replacement of while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding strength volume responses hydrate‐bearing sediments during shear. This study employs a custom‐made apparatus to investigate mechanical volumetric behaviors dioxide subjected direct The results show that both peak residual strengths increase with increased saturation vertical stress. Hydrate contributes mainly...

Abstract Freezing point and unfrozen water content are key parameters in modeling the heat mass transfer under cyclic change of atmosphere temperature. It is theoretically revealed relation between measured pore pressure true with physicochemical interactions. A new generalized Clapeyron equation derived, which addresses relationship among water, ice‐liquid capillary pressure, solution concentration for frozen soil. The applied to derive expressions freezing soils at various thermodynamical...

Abstract Freezing and thawing of soil have a significant impact on the thermal‐hydrological processes in cold regions. point unfrozen water content are key variables characterizing freezing soil. The testing results show that is independent initial nonsaline silt, based which unified model for characteristic curve (SFCC) presented. SFCC describes relationship between temperature variably‐saturated saline soils. It also demonstrated can describe variation with respect to salt concentration....

Although soil–rock mixtures (S-RMs) exist extensively on Earth's surface, their mechanical behaviors remain elusive. In this study, a series of large-scale direct-shear tests was conducted to investigate the S-RMs composed weathered basalt with different rock block contents, including stress–strain relationship, dilatancy, particle breakage, and shear strength. The results indicate that S-RM shows more pronounced strain-hardening behavior as its content increases. For there is power law...

An experimental investigation was conducted to uncover how artificial manipulation of layer charge montmorillonite regulates its swelling and hydration behavior hence find novel applications such as CO 2 capture. Charge-reduced montmorillonites (CRMs) were prepared via the Li-fixation technique, followed by characterizing their diverse physical, chemical, hydration, properties, including Atterberg limits, cation exchange capacity, water adsorption isotherms, basal spacing variability,...

To exploit the resource of methane hydrate, it is crucial to understand mechanical behavior hydrate-bearing sediments. In this paper an elastoplastic constitutive model developed for describing gas hydrate–bearing soils (GHBS). address effect hydrate occurrence habits, concept effective degree saturation introduced, and stress stresses are redefined response GHBS. Within context, a yield or loading function while considering bonding hydrate; thus, can expand shrink as forms dissociates....

Abstract Based on the chemical potential equilibrium of water, a generalized equation phase is presented for pore hydrate, which relates temperature depression hydrate to capillary pressure and osmotic pressure. The relationship between unhydrated water content can be characterized by soil‐water characteristic curve (SWCC). Uniting SWCC yields soil hydration (SHCC), expresses hydrate. A series experiments are performed, validating concept SHCC. From SHCC, surface determined in space...

Abstract Hydrate dissociation‐induced deformation plays a crucial role in reservoir stability during the exploitation of natural gas hydrates. During depressurization‐induced dissociation pore hydrate, both hydrate saturation loss and effective stress rise tend to enhance deformation. Previous studies have not been able distinguish between deformations caused by these two factors. In this study, triaxial tests were conducted on carbon dioxide hydrate‐bearing sediments with constant but...

A constitutive model of unsaturated soils is developed by incorporating the concept intergranular stress into framework modified Cam–Clay model. Within this context, degree saturation viewed as an internal state variable, so that soil–water retention function appears naturally evolution equation for volume fraction water. The new not only has a neat structure but also includes fewer material parameters compared to other models. volumetric-hardening law proposed taking account effect...

Abstract Water transport in large‐specific surface soil is controlled by microstructure and soil‐water interaction. In this paper, interaction confined water dynamics as well are studied combining the nuclear magnetic resonance technique mercury intrusion porosimetry. It revealed that during a drying process pore drainage occurs sequentially from larger pores to smaller pores, parameter ρ 1 appears be well‐defined quantity at content above one layer, below which shows different trend. With...

The principle of effective stress is the most fundamental and important in soil mechanics. It serves as foundation modern This paper starts with a discussion expressions for unsaturated soils. relationship between total each phase soils developed based on three-phase equilibrium equations representative element volume (REV). expression average skeleton stress, defined then derived. consistent equation derived deformation work energy conservation equation. general philosophy definition...

The phase equilibrium and mechanical behaviors of natural gas hydrate-bearing sediment are essential for exploiting hydrate reservoirs. In heating closed systems, the temperature-pressure path deviates from that pure bulk hydrate, reflecting porous media effect in equilibrium. A generalized equation was established sediments, which indicates both capillary osmotic pressures cause curve to shift leftward on plane. contrast always contains a certain amount unhydrated water, keeps with within...

The variation of adsorbed water content is the core issue in study temperature effect clay. and distribution soil detected by NMR technique, combined with difference suction, freezing point capillary water, a fast, nondestructive method developed which can be used to determine soil. dry density determined method. result indicates that at room temperature, samples decreases increasing density. This mainly due reducing space particles during increase overlapping electric double layer. For...

Abstract The evolution of the liquid‐vapor interface plays a key role in multiphase flow, heat and mass transfer, fluid phase change porous media. In soil water evaporation process, vaporization occurs only on interfaces rather than apparent surface. Yet, evolve with high distortion great complexity along drying path. Hence microscale characteristics especially geometrical topological features are barely investigated. this work, we scanned glass bead samples using X‐ray micro tomography...

A series of phase equilibrium tests were performed to explore the influence various experimental conditions, including initial water content, dry density, and salt on behavior methane hydrate in fine- coarse-grained sediments. The results indicate that condition pore is significantly influenced by adopted conditions sediment types. It shown equilibrium, a unique relationship (the soil hydration characteristic curve (SHCC)) exists among temperature shift, unhydrated water, amount dissolved...

Extraction of methane hydrate from subseafloor reservoir may potentially trigger seabed slides and induce subsidence. To address the problems, it is crucial to properly characterize phase equilibrium condition pore shear strength soil. As one key constitutive components, enforces a constraint over gas pressure, temperature unhydrated water content. Such constraint, however, has been traditionally ignored in analyzing mechanical behavior hydrate-bearing In this paper, series stepwise...