Interaction Effect Analysis Of Nuclear Power Plant CAP1400 Structure-foundation In Non-rock Site

Nuclear power as a clean energy, and has broad development prospects, to solve the current problems of China's energy have great significance. Because the nuclear power project has has the potential radiological risk, it must to make a strict analysis and evaluation for the response of nuclear power plant structures under the earthquake action when the design, to ensure that the nuclear power plant with adequate seismic capacity.In recent years, the nuclear power in a period of rapid development in China, and actively promote the localization of AP1000 nuclear power plant, the CAP1400 as the representative of the independent design of nuclear power projects are also in the period of research and development. In the application and continuous promotion of AP1000 and CAP1400 standard design nuclear structure, inevitably will face the problem of selecting the non-rock site. The new nuclear island design of AP1000 nuclear power generating units make the foundation from the bedrock site expand to the soil site. Therefore, study on the effect of seismic response of the nuclear island structure in non-rock site has the important theoretical significance and application requirements.The problem of seismic response of nuclear power plant in non-rock sites were studied, considered the foundation and structure interaction, system and further study on the problem of the seismic response of the nuclear power plant in non-rock site, and provide the basis for nuclear power plant in site selection and safety design. The main work of this paper is as follows:(1) Soil shear wave velocity have an impact for the nuclear island structure modal, with the different soil shear wave velocity, the damping of the nuclear island structure changed; Shear wave velocity is smaller, the soil more soft, the soil structure interaction for the influence on dynamic characteristics of the structure is greater.(2) Select AP1000 spectrum, RG1.60 spectrum as the input ground motion, study the seismic response of nuclear power plant CAP1400 structure under five kinds different shear wave velocity of the foundation in non-rock site. Calculation and analysis show that the non-rock ground foundation and structure interaction effect makes the structure response have a significant change, but the main performance is the influence of the high frequency of the acceleration response spectrum, and has little effect on the low frequency value.With the increase of foundation soil shear wave velocity values, the nuclear island foundation and safety shell parts of ground motion acceleration increase, ground motion displacement decreases, stress increases, the peak value of acceleration response spectrum corresponds to the cycle decreases, seismic response rules of structure is similar in different ground motion inputs.(3) The non-rock ground foundation and structure interaction effect makes the actual ground motion input of nuclear structure and structure response have a significant change, but with shear wave velocity increase, namely foundation from soft to hard, the effects of foundation structure system in nuclear island gradually decreased; When the soil shear wave velocity values increased to 1250m/s, response calculation results with no nuclear structure in the free field is basically the same. For this reason, it is recommended for CAP1400 island structure seismic analysis, without considering soil structure interaction effects when shear wave velocity of rock soil values greater than 1250m/s, which can the nuclear island foundation input motion in the free field seismic action; when the shear wave velocity of rock soil is less than 1250m/s, the influence of non-rock site should be analyzed and considered.(4)In the same soil parameters and seismic input, the shaking table test results and the same scale numerical analysis results of nuclear power plant CAP1400 structure in non-rock structure were compared, analyzed the differences between the tests and numerical simulations. The comparison shows that the acceleration response spectrum of the finite element numerical analysis results are basically the same as that of the test results at lower frequency(period than 0.2S), but the peak acceleration and acceleration response spectrum of the shaking table test result is larger than that of the numerical analysis.(5) In the same parameters of foundation soil and the corresponding ground motion input, respectively on the scale model and full-scale model of non-rock site cap1400 nuclear structure were finite element numerical simulation, analysis the influence of scale model on the seismic response. Research show that scale model and full-scale model of acceleration response spectra are basically same, but full scale model of the response spectrum generally increase slightly, scale model of the finite element analysis results are closer to the test results.