Mechanical characteristics and localized deformation of Methane Hydrate-bearing sand using high pressure plane strain shear tests

Abstract

Methane Hydrate (hereafter referred to as MH) is being researched and developed in order to prepare for production in the Nankai Trough of Japan. The grain size distribution and the degree of MH saturation of MH bearing sand varies based on location with varying fines content. Also, the shear behaviour is affected by particle shape. In order to investigate the effect of the characteristics of host sand on the shear behaviour of MH-bearing sands, MH was artificially produced in specimens composed of four kinds of materials with varying particle shape, fines content and degree of MH saturation. In this study, a high stress and low temperature triaxial plane strain testing apparatus was used. A marked increase in stiffness and strength was observed in all MH-bearing materials. In the case of glass beads, higher peak stress appeared in MH-bearing material than that without MH and the softening behaviour of MH bearing sand after peak strength was most predominant. In the case of MH-bearing sand, an increase in fines content leads to an increase in strength. An increase in degree of MH saturation leads to an increase of the angle of the shear band and the width of shear band becomes narrower.