Based on continuum mechanics, we have developed a model for semi quantitative estimating effects of phase continuity on flow strength of two phase rocks including partially melted or crystallized rocks. Calculations o...Based on continuum mechanics, we have developed a model for semi quantitative estimating effects of phase continuity on flow strength of two phase rocks including partially melted or crystallized rocks. Calculations of the bulk flow strength of composite rocks as functions of the volume fraction, geometrical shape and continuity of the constitutive phases involve in numerically solving two non linear equations and thus are easy to be performed. The model has been justified by a good agreement between the predicted and measured results on diabase (64% clinopyroxene and 36% plagioclase) in the range of experimental temperatures and strain rates. It is believed that the present model could provide an approximate estimate for the rheological evolution of magmatic rocks during their life cycle of melting crystallization deformation.展开更多
A two phase model of rock was proposed in order to investigate the mechanism of brittle fracture due to uniaxial compression, in which rock was considered to be a composite material consisting of hard grains and collo...A two phase model of rock was proposed in order to investigate the mechanism of brittle fracture due to uniaxial compression, in which rock was considered to be a composite material consisting of hard grains and colloids. The stress state in colloid region near grains was calculated using Finite Element Method (FEM). The influence of the tensile stresses on the crack initiation and failure process of brittle rock subjected to uniaxial compression was investigated by numerical experiments. The FE results show that tensile stresses are induced easily in the neighboring area of hard grains with the maximum value near grain boundaries. The distribution of tensile stresses depends on the relative position of hard grains. The cracks initiated just near the boundary area of hard grains, which was governed by tensile stress. These results clearly reveal the micro fracture mechanism of brittle rock loaded by uniaxial compression. It can be concluded that the failure mode of brittle rock under uniaxial compression is still tensile fracture from the point view of microstructure. However, since the wide colloid region is still under compressive stress state, further propagation of boundary cracks through this region obviously needs more external load, thus causing the uniaxial compressive strength of rock much higher than its tensile strength obtained via Brazilian (splitting)展开更多
文摘Based on continuum mechanics, we have developed a model for semi quantitative estimating effects of phase continuity on flow strength of two phase rocks including partially melted or crystallized rocks. Calculations of the bulk flow strength of composite rocks as functions of the volume fraction, geometrical shape and continuity of the constitutive phases involve in numerically solving two non linear equations and thus are easy to be performed. The model has been justified by a good agreement between the predicted and measured results on diabase (64% clinopyroxene and 36% plagioclase) in the range of experimental temperatures and strain rates. It is believed that the present model could provide an approximate estimate for the rheological evolution of magmatic rocks during their life cycle of melting crystallization deformation.
文摘A two phase model of rock was proposed in order to investigate the mechanism of brittle fracture due to uniaxial compression, in which rock was considered to be a composite material consisting of hard grains and colloids. The stress state in colloid region near grains was calculated using Finite Element Method (FEM). The influence of the tensile stresses on the crack initiation and failure process of brittle rock subjected to uniaxial compression was investigated by numerical experiments. The FE results show that tensile stresses are induced easily in the neighboring area of hard grains with the maximum value near grain boundaries. The distribution of tensile stresses depends on the relative position of hard grains. The cracks initiated just near the boundary area of hard grains, which was governed by tensile stress. These results clearly reveal the micro fracture mechanism of brittle rock loaded by uniaxial compression. It can be concluded that the failure mode of brittle rock under uniaxial compression is still tensile fracture from the point view of microstructure. However, since the wide colloid region is still under compressive stress state, further propagation of boundary cracks through this region obviously needs more external load, thus causing the uniaxial compressive strength of rock much higher than its tensile strength obtained via Brazilian (splitting)
