Nonlinear Damage Rheological Mechanical Model For Complex Rock Of High DAM Slope And Its Engineering Application

The large deformation and failure of high dam was closed to the rheological deformation of weak intercalated rock mass and hard brittle rock mass in dam foundation under long-term loads. The hard brittle diabase and weak intercalated rock mass in dam foundation of Dagangshan hydropower station were taken for research object, the research methods combined of experiment, theoretical analysis and numerical simulation were used. Based on the triaxial rheological experiment results of hard brittle rock in laboratory and in-situ compressive creep test results under large rigid bearing plate of weak intercalated rock mass, the rheological mechanical properties of rock was analysed by use of nonlinear rheological theory and damage mechanics. Nonlinear rheological constitutive models of rock were established, and the long-term stability of slope project in dam zone of hydropower station was predicted.The main research work focused on the following.(1) In order to know about the rheological properties of rock specimens in Dagangshan hyeropower project, triaxial compression rheological experiments with rock specimens under different stress load paths were carried out on the rock servo-controlling rheology testing machine. The deformation characteristics in triaxial rheological process were discussed in detail. The SEM experiments were carried out for typical fracture shaping of rock specimens, the influence of rock mesoscopic structure change on its macroscopic strength was studied, and the rheological fracture mechanism of rock under complex stress states was put forward.(2) Based on in-situ compressive creep tests under rigid bearing plate, theory analytical formulas'method for inversion of visco-elastic compressive creep parameters under rigid or flexible plate was established. The rheology parameters were obtained through the combination of theoretical analytic inversion and the experiment data.(3) Based on deformation characteristics of specimens in the triaxial rheological experiments, a new nonlinear visco-elasto-plastic rheological model was established which could describe the primary creep, steady-state creep and tertiary creep perfectly, and the yield approach index(YAI) was taken as the discriminant criteria of piecewise function in three dimensional creep equation.(4) Based on deformation characteristics of in-situ compressive creep tests under rigid bearing plate, a nonlinear damage rheological model was proposed in which the creep parameters of the weak intercalated rock mass were weakened with time gradually, and this model could describe the visco-elastic deformation, visco-plastic deformation and damage deformation perfectly.(5) Secondary development of nonlinear visco-elasto-plastic rheological model for hard brittle rock and nonlinear rheological damage model for weak intercalated rock mass were carried out in FLAC3D.(6) The improved Particle Swarm Algorithm(PSO) was programmed for the rheological parameters inversion, which achieved rheological parameters rapidly and intelligently through back analysis. The rheological parameters of weak intercalated rock mass were got by numerical calculation inversion method.(7) The triaxial rheological volume strain method and residual strain method in loading-unloading rheological test were put forward to determine the long-term strength of hard brittle rock.(8) By using the nonlinear visco-elasto-plastic rheological model of hard brittle rock and variable parameters-based damage rheological model of weak intercalated rock mass,3D excavation and rheological numerical calculation of slope in dam zone of Dagangshan hydropower station was carried out, which predicted the long-term deformation characteristic after excavation of rock engineering in complex stress state.