Strengthening mechanism of cemented hydrate‐bearing sand at microscales. Issue 14 (18th July 2016)

• Record Type: Journal Article
• Authors: Yoneda, Jun; Jin, Yusuke; Katagiri, Jun; Tenma, Norio
• Is Part Of: Geophysical research letters. Volume 43:Issue 14(2016)
• Page Start: 7442
• Page End: 7450
• Publication Date: 2016-07-18
• Subjects: hydrate -- micro‐X‐ray CT -- triaxial test -- shear -- strength; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL069951
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: On the basis of hypothetical particle‐level mechanisms, several constitutive models of hydrate‐bearing sediments have been proposed previously for gas production. However, to the best of our knowledge, the microstructural large‐strain behaviors of hydrate‐bearing sediments have not been reported to date because of the experimental challenges posed by the high‐pressure and low‐temperature testing conditions. Herein, a novel microtriaxial testing apparatus was developed, and the mechanical large‐strain behavior of hydrate‐bearing sediments with various hydrate saturation values ( Sh = 0%, 39%, and 62%) was analyzed using microfocus X‐ray computed tomography. Patchy hydrates were observed in the sediments at Sh = 39%. The obtained stress‐strain relationships indicated strengthening with increasing hydrate saturation and a brittle failure mode of the hydrate‐bearing sand. Localized deformations were quantified via image processing at the submillimeter and micrometer scale. Shear planes and particle deformation and/or rotation were detected, and the shear band thickness decreased with increasing hydrate saturation. Key Points: A microtriaxial testing apparatus was developed for analyzing hydrate‐bearing sand via X‐ray computed tomography Soil particles and hydrate in the shear band significantly move and rotate at the microscale The thickness of the shear band decreased with increasing hydrate saturation