Experimental study on the weakening law of gas hydrate-bearing sand-mining well interface under dissociation condition
The dissociation of gas hydrate leads to the reduction of the bearing capacity of the interface between gas hydrate-bearing soil and mining well,resulting in discontinuous deformation such as dislocation and sliding,which directly affects the stability of the mining well.In order to study the weakening law of gas hydrate-bearing soil-mining well interface under dissociation conditions,based on the developed low-temperature and high-pressure gas hydrate generation and triaxial test equipment,shear tests of gas hydrate-bearing sand-mining well interface under dissociation conditions are carried out,and the statistical damage model of gas hydrate-bearing sand-mining well interface considering dissociation effect is constructed.As a result,the interface is in strain softening state before gas hydrate dissociation,and the shear strength and dilatancy increase with the increase of saturation.The interface is in strain hardening state after dissociation,and the shear strength increases with the increase of saturation,but the dilatancy is slightly affected by it.In addition,comparing with before dissociation,the shear strength,cohesion and dilatancy of the interface decreased after dissociation,showing significant weakening characteristics.Therefore,considering the strength of the interface finite micro cells obeys Mohr-Coulomb strength criterion and double-parameter Weibull random distribution,the interface statistical damage model which can better simulate the failure of gas hydrate-bearing sand-mining well interface caused by dissociation is established,the relationships of the parameters m and F0 in the model with gas hydrate saturation,effective confining pressure and dissociation are analyzed.The relevant results can promote the research on the basic theory and key technology of gas hydrate exploration and development.
soil mechanicsgas hydratedissociationgas hydrate-bearing sand-mining well interfaceinterface weakeningstatistical damage model
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