Hypoplastic Modeling For Rockfill And Numerical Analysis Of Concrete Face Rockfill Dam

Rockfill is the part for support in the structure of a concrete face rockfill dam (CFRD) and its deformation and stress state decide the operating performance of the CFRD. Based on the study about the engineering property of rockfill, the present dissertation creates a new hypoplastic model for rockfill. Combining theoretic analysis and numerical calculation, the hypoplastic model can include the main mechanical properties of rockfill and has its own characters comparing with other conventional constitutive models of rockfill. Some special investigation results obtained from the study are useful for the deeper understanding and analysis of stress and deformation of CFRDs. The main concrete investigations involved in the research work are as follows.(1) Analyzing the compressibility, shear resistance and deformation principle and summarizing the main mechanical properties of rockfill, such as nonlinearity, barotropy, dilatancy, anisotropy and so on, for the basis of hypoplastic modeling of rockfill. Furthermore, some conventional constitutive models of rockfill are also analyzed and summarized.(2) Introducing the origin, development and current investigation level at home and abroad of hypoplastic theory systematically, Some basic mathematic and mechanical knowledge of hypoplastic theory are put forward and the general format and mechanical properties are discussed in the paper.(3) The change characteristics of the void ratio of granular materials are investigated. Based on the analysis of mechanical behavior of rockfill, the Gudehus-Bauer hypoplastic model is modified and introduced into constitutive modeling of rockfill. Theoretical and numerical analysis show the model can have the main mechanical properties of rockfill. A complex method for the identification of the material basic parameters involved in the model is improved based on the partial test data and optimal back analysis. It is useful for the determination of the 10 parameters for the modified hypoplastic model.(4) The data from several conventional geotechnical tests obtained from literatures are numerical simulated and confirmed with the new hypoplastic model and the mechanical properties of the model are deeply further discussed based on the calculation results.(5) A respective finite element code has been implemented on the basis of the modified hypoplastic model and the reasonable deformations and stresses of a CFRD are gotten with the program. Some new instructive results are derived using the hypoplastic model.(6) Summarizing the current theory on 3D nonlinear FEM for CFRDs.(7) Modeling the viscosity of rockfill using the visco-hypoplastic theory and creating the interface model between concrete face slab and supporting layer based on hypoplastic theory.