The Constitutive Model Of Rockfill Based On Property-dependent Plastic Potential Theory And Finite Elemeot Analysis About Side Slope

The rockfill is a commonly used material in the construction of civil engineering and hydraulic engineering.It is affected by factors such as particle breaking and arrangement,size distribution,stone formation,and permeability,and its strength and deformation characteristics are so complex.The strength and deformation characteristics of rockfill are not only affected by its macroscopic stress state and path,but also by the changing characteristics of its mesoscopic characteristics such as its geometric features and spatial arrangement.When the rock aggregates with different gradation and particle arrangement are under the same stress conditions,the strength deformation characteristics exhibited by them are very different.With the strong permeability of rockfill materials,this is a large deformation and stability of earth-rock dams,slopes,etc.the description brings great challenges.for this reason,based on the material-related critical state theory,the material properties related to the plastic potential theory,combined with the fractal theory and the results of the macroscopic study of sand,the rockfill material constitutive model was established,the finite element program based on the ABAQUS development model,and the use of geotechnical test results and engineering examples are used to verify the model.Its main conclusions and work are as follows:(1)The constitutive model of rockfill materials was established based on the theory of property-dependency fractal theory was used to characterize the regularity of particle distribution and particle breakage due to the effect of particle size distribution and particle breakage on the fractal dimension.The anisotropic state variables and the fractal dimension of rockfill materials defined by the macroscopic and microscopic combination were used to characterize the distribution of rockfill particles.The rules of yield and failure of rockfill materials have been established by the law of changes in numbers,and the critical state equations considering the microscopic fabric,fractal dimension,particle breakage,and stress state have been established based on the related concepts of materials and rockfill strength test results.The material properties of the structure of the plastic potential theory deduced the rockfill accounting equations,and establish the hardening criteria affected by the critical state,in the new potential theory under the framework of the establishment of a general stress space rockfill constitutive model.(2)The model verification was performed using the conventional triaxial drained test of rockfill.The new model establishes the relationship between the mesoscopic scaled particle and the stress state of the rockfill materials,to use the anisotropic state variables to reflect the anisotropy due to the different particle arrangement rules,the primary anisotropy and the secondary anisotropy,reflecting the mesoscopic anisotropy of stress-induced anisotropy and primary anisotropy are considered.At the same time,the influence of factors such as the fractal dimension of the rockfill,particle breakage,and gradation on its critical state line is considered.The model test results are verified by the discharge strength test of rockfill materials.The performance of the critical state description under various stress paths simulate its three-dimensional spatial intensity variation and its intensity variation in the ?-plane,and the validity and rationality of the simulation verification model for the stress-strain relationship.(3)Based on ABAQUS to develop rockfill model of finite element program.Using the user-defined material interface of ABAQUS commercial software to carry out secondary development of the model,using the Fortran language to compile the calculation subroutine UMAT of the rockfill material elastoplastic stiffness matrix,implanting the subroutine into the ABAQUS program to perform the finite element unit on the model.To establish the finite element model of the biaxial and triaxial tests.The stress-strain relationship showed that the development program was capable of grasping the strength and deformation characteristics of the rockfill,at the same time,it is able to better simulate different fractal dimensions,particle breakage,gradation,and microscopic orthotropic factors and other factors to describe the deformation behavior of rockfill materials,and can also describe deformation laws of rockfill materials with complex stress state lines such as rotation of principal stress axes.(4)Analyze the deformation regularity and stability of rockfill slope in three-dimensional space.The 3D finite element analysis model for slopes.Considering the actual structural composition of slopes and earth-rockfill dams,the slope was divided into three layers.The material parameters of each layer were set according to the engineering background and the model parameters were calculated hierarchically.soil and water conservation were also considered to maintain the requirements for slope design,use the constitutive model of rockfill materials in this paper to analyze the stability and deformation of the slope,and use the solid-liquid coupling function in the software to simulate the stability of coal gangue slope after rain.The simulation results can be grasped.The key slope deformation and permeability characteristics.