Series of testing on coarse grained soils were carried out with a true triaxial testing apparatus.The loads were applied from the major principal and minor principal directions,respectively,to simulate the constructio...Series of testing on coarse grained soils were carried out with a true triaxial testing apparatus.The loads were applied from the major principal and minor principal directions,respectively,to simulate the construction and water impounding process of a rock fill dam.The stress and strain relationships induced by the different loading methods were investigated.A remarkable stress-induced anisotropy under complex stress state was observed.Contrary to popular assumptions in traditional numerical analysis and constitutive models,it was found that different elastic modulus and Poisson ratio exist in different principal directions in rock fill dams.From the testing results,an anisotropic constitutive model based on Duncan-Chang nonlinear model is presented to overcome the limitations of axi-symmetric assumptions in conventional triaxial experiments and constitutive models.Both models were then applied in FEM analysis of an under-construction earth core high rock soil filled dam with the focus on hydraulic fracturing.The study reveals the major biases that exist when numerical analysis and constitutive models do not give serious consideration to the intermediate principal stress and anisotropy effects in soil rock built structures.展开更多
Rockfill materials have been widely used in the construction of rockfill dam,railway and highway subgrade due to its high filling density,good compaction performance,strong water permeability,small settlement deformat...Rockfill materials have been widely used in the construction of rockfill dam,railway and highway subgrade due to its high filling density,good compaction performance,strong water permeability,small settlement deformation and high bearing capacity.A reasonable constitutive model for rockfill materials is very important for engineering computation and analysis,and has a great development space.Based on the crushing stress and spatial mobilized plane(SMP),a state parameter that can comprehensively reflect the anisotropy and grain crushing is proposed.This state parameter is used to improve the MPZ model(a modifed ZienkiewiczⅢmodel),so that a generalized plastic model is constructed to describe the stress and deformation characteristics of rockfill materials in engineering.The validity of the developed model is verified by a series of conventional triaxial tests with different inclination angles of the compaction plane.The variation trend of the constructed anisotropy indexωcan reflect the non monotonic variation of the deformation and strength of rockfill with the direction angle of large principal stress,so the model can reflect the obvious difference caused by the initial anisotropy of rockfill on the mechanical properties.展开更多
基金Project(50809023)supported by the National Natural Science Foundation of ChinaProject(2015B17714)supported by the Fundamental Research Funds for Central Universities,China
文摘Series of testing on coarse grained soils were carried out with a true triaxial testing apparatus.The loads were applied from the major principal and minor principal directions,respectively,to simulate the construction and water impounding process of a rock fill dam.The stress and strain relationships induced by the different loading methods were investigated.A remarkable stress-induced anisotropy under complex stress state was observed.Contrary to popular assumptions in traditional numerical analysis and constitutive models,it was found that different elastic modulus and Poisson ratio exist in different principal directions in rock fill dams.From the testing results,an anisotropic constitutive model based on Duncan-Chang nonlinear model is presented to overcome the limitations of axi-symmetric assumptions in conventional triaxial experiments and constitutive models.Both models were then applied in FEM analysis of an under-construction earth core high rock soil filled dam with the focus on hydraulic fracturing.The study reveals the major biases that exist when numerical analysis and constitutive models do not give serious consideration to the intermediate principal stress and anisotropy effects in soil rock built structures.
基金Project(2017YFC0404802)supported by the National Key R&D Program of ChinaProjects(U1965206,51979143)supported by the National Natural Science Foundation of ChinaProject([2018]5630)supported by the Talents of Guizhou Science and Technology Cooperation Platform,China。
文摘Rockfill materials have been widely used in the construction of rockfill dam,railway and highway subgrade due to its high filling density,good compaction performance,strong water permeability,small settlement deformation and high bearing capacity.A reasonable constitutive model for rockfill materials is very important for engineering computation and analysis,and has a great development space.Based on the crushing stress and spatial mobilized plane(SMP),a state parameter that can comprehensively reflect the anisotropy and grain crushing is proposed.This state parameter is used to improve the MPZ model(a modifed ZienkiewiczⅢmodel),so that a generalized plastic model is constructed to describe the stress and deformation characteristics of rockfill materials in engineering.The validity of the developed model is verified by a series of conventional triaxial tests with different inclination angles of the compaction plane.The variation trend of the constructed anisotropy indexωcan reflect the non monotonic variation of the deformation and strength of rockfill with the direction angle of large principal stress,so the model can reflect the obvious difference caused by the initial anisotropy of rockfill on the mechanical properties.
