DISCRETE ELEMENT ANALYSIS OF EFFECT OF PARTICLE BREAKAGE ON MACROSCOPIC AND MICROSCOPIC MECHANICAL PROPERTIES OF HYDRATE-BEARING SEDIMENT MATRICES
Based on"particle fragmentation replacement method",a discrete element model is developed for hydrate-bearing sediment matrices,which can reflect the behavior of particle breakage.A comparative triaxial shear test is conducted for breakable and non-breaking models,demonstrating that particle breakage has significantly influence on the strength and shear dilatancy characteristics.In addition,the"particle size expansion method"is applied to improve the simulation effect of the model on the volumetric strain and particle breakage degree.A series of simulated triaxial drainage shear tests are conducted under low and high effective confining pressures to evaluate the meso-mechanical characteristics.The results show that with the increase in the effective confining pressure,the strength,stiffness and average normal contact force of the specimen increase,and the force chain gradually is strengthened.The force chain network becomes denser and changes from annular to vertical,while the particles moving along the axial direction at both ends of the sample increase.The particle breakage primarily occurs during the early shearing.The mechanical coordination number and average normal contact force gradually increase with shearing.At the end of the shearing,A strong chain structure and an"X"shape shear band emerges within the sample,and the particles'motion varies from chaotic to top-and bottom-inward.
natural gas hydratenumerical simulationmechanical propertiessand breakageparticle size expansion method
NETL
NSTL
万方数据
