Study On Elasto-plastic Method And Aseismic Measures Of High Earth-rockfill Dam During Earthquake

Reasonable seismic design methods and aseismic measures should be proposed according to the characteristic of damages and failure mechanism of structures, and anti-seismic mechanism of the corresponding measures should be studied, which are the key problems and aims in aseismic research on high earth-rockfill dam. The research is supported by the National Science Foundation of China "Study on Aseismic Meassures of High Earth-rockfill Dam in Strong Earthquake Zone" (No.50679093) and the Mega-project of Natural Science Foundation Program "Research on Earthquake Disaster Simulation and Safety Control Method of High Earth-rockfill Dam" (No.90815024). In this paper, the nonlinear elastoplastic analysis method of FLAC was used and the dynamic response characteristics and failure mechanism of high dam were studied firstly. Secondly, the numerical simulation was used and good agreements were obtained between the numerical results and those from shaking table tests. Thirdly, the effect of seismic of geogrid reinforcement measures was analysed. And finally an engineering example was verified using numerical simulation. The main contents of the current research are as follows:(1) The main purpose is to study the seismic response and failure mechanism of high earth-rockfill dams under earthquakes by using dynamic elasto-plastic methods. The results of the FEM verify the reasonableness of FLAC procedures in simulating the seismic response of high earth-rockfill dams. The main concerned aspects are the shear strain, the permanent deformation as well as the grid deformation during earthquakes. At the same time, the influences of parameters as dam height, slope and ground motion on failure modes of dams are systematically studied.(2) Based on two-dimensional analysis, the main purpose is to study the seismic response of high earth-rockfill dam in narrow valley by the method of three-dimensional nonlinear dynamic elasto-plastic analysis method. The distributions of shear strain and permanent deformation of different valleys of the dam are provided.(3) The seismic response, stability and reinforced the aseismic measures of earth-rockfill dam was studied based on shaking table test and numerical simulation. An elastic-plastic analysis method was applied to simulate and analyze the dynamic failure process and permanent deformation of earth-rockfill dam slope under seismic motion. At the same time, the stability of slope, the depth of slip surface and the effectiveness of reinforcement were investigated by the method of quasi-static. The calculated results and those obtained from shaking table tests are compared.(4) Based on the dynamic response of high earth-rockfill dam, a dynamic elasto-plastic analysis method for the high earth-rockfill dam slope reinforced with geogrids was set up. Based on this model, the behavior, deformation and failure mechanism of such a high earth-rockfilled dam slope, as well as the geogrid connection, the length, the spacing and the stiffness on the deformation of the high earth-rockfill dam are analyzed.(5) The Lianghekou high core rock-fill dam was taken as an example. The dynamic response of the dam and permanent deformation is analyzed and compared with the known values. At the same time, the effects of aseismic reinforcement measures are studied. And the maximum aseismic capability of dam is preliminarily evaluated from the stability and deformation after reinforcement.