Investigating the shear band of methane hydrate-bearing sediments by FEM with an elasto-plastic constitutive model

In order to investigate the formation of the shear band in methane hydrate-bearing sediments (MHBS), an elasto-plastic constitutive model was proposed and implemented into a FEM software Abaqus. After verification of the model implementation by UMAT, a series of biaxial compression test simulations on MHBS samples were performed. Then. the verified UMAT was adopted to simulate the characteristics of the shear band of the MHBS samples, and the 'weak element' was set in the MHBS samples to simulate the influence of nonuniform density on the deformation behavior of the MHBS. Finally, the simulation results were analysed, with emphasis on the characteristics of the shear band. The results showed that: (1) during the test, the shear band coalesces through the 'weak element' and the inclination of the shear band is 48A degrees; (2) the presence of the shear band is the forerunner of element destruction; (3) the shear band occurs before the peak shear strength and the width of the shear band grows larger during loading; and (4) the bifurcation of the stress and volumetric response of elements within the shear band is more obvious during the tests.