Time-domain Analysis Of The Soil-nuclear Power Structure Interaction Based On High-performance SBFEM

It is particularly important to actively carry out seismic studies of the nuclear structure to strengthen the security of nuclear power and the ability of nuclear structure against unforeseen disasters. Considering the soil-structure interaction in the time domain, a million-kilowatt nuclear power plant structure has been taken as the object of this study, which established a scaled boundary finite element dynamic model based on the acceleration pulse response function. The dynamic responses of the plant superstructure and the floor response spectrum have also been calculated under the conditions of the excavated ground. It could provide references for the seismic safety evaluation of nuclear power plants. The main content is summarized as follows:(1) The rationality of the infinite domain foundation model, which directly affects seismic safety of the nuclear power plant structure and equipment, is an important basis for efficient and precise plant-basis-foundation dynamic interaction in time-domain numerical analysis. With the high performance scaled boundary finite element method which based on acceleration impulse response function, it combined with the real parameters of foundation made a detailed analysis on the solution of the infinite foundation interaction and studied the engineering usability of the model by comparing with the viscoelastic boundary model and the ASCE model. The results show that the model, on condition of a high accuracy, reduces the convolution calculation and provides a good numerical stability and a high sensitivity to the parameters of the excavation pit, which has good engineering practical prospect.(2) Dimensional analysis was introduced in the calculation of the acceleration impulse response function of which the dimensionless form was given. In the actual calculation, it could be converted into real acceleration impulse response function by multiplying a coefficient related to the material parameters of the foundation. This method can effectively reduce the calculation errors.(3) A million-kilowatt nuclear power plant structure has been simplified to the quality-beam element model and connected to the HPSBFEM dynamic foundation model. Then, the dynamic responses of the plant superstructure and the floor response spectrum have been calculated by Newmark-P method. The result was compared with the lumped parameters model recommended by ASCE and the viscoelastic artificial boundary model. The results showed that the SBFEM model was mathed well with the lumped parameter model in the homogeneous soil conditions. But compared with the viscoelastic boundary model, it realized that the change of the earth wave under the excavation condition should be considered. The accuracy of the result caculated separately by the HPSBFEM model and the viscoelastic boundary model was quite close. (4) Nuclear power plant site conditions are generally more complex. There are some differences in shear-wave velocity of the foundation with the foundation depth. The ground motion input was determined by viscoelastic artificial boundary method. A conservative analysis of the HPSBFEM model applicated in the layered ground conditions was applied.