Characterization of stress–dilatancy behavior for methane hydrate-bearing sediments

Abstract

To evaluate the stability of seabed ground during gas hydrate exploitation, a constitutive model that can appropriately estimate the mechanical properties of methane hydrate-bearing sediments must be established. A better understanding of the stress–dilatancy characteristics is crucial in modeling the stress–strain behavior of methane hydrate-bearing sediments under complex loading paths. This study presents a compressive analysis of the effects of several factors on the stress–dilatancy behavior of methane hydrate-bearing sediments. The dilatancy behavior of methane hydrate-bearing specimens synthetized in the laboratory and natural hydrate-bearing samples acquired in the field are compared. Results show that the hydrate saturation, temperature, porosity, and hydrate formation pattern affect the peak stress ratio, dilatancy rate, and critical state stress ratio of methane hydrate-bearing sediments. However, the effect of effective confining pressure on the stress–dilatancy curve is minimal. Different hydrate formation methods yield different hydrate morphologies; consequently, the dilatancy behavior of methane hydrate-bearing sediments is altered significantly. Differences observed between synthetized specimens and natural samples may originate from various hydrate morphologies. The stress–dilatancy relationship of methane hydrate-bearing sediments is interpreted and described using Rowe's theory. Furthermore, the dilatancy behavior of methane hydrate-bearing sediments and cemented sands under similar test conditions is compared.