Based on a large number of strong vibration observation records of Japan's KiK-net network, this thesis carried out a statistical analysis of the ground motion attenuation relationship of different sites and the correlation between the site conditions of observation stations and the strong vibration recording characteristics, conducted a comparative study of the site classification methods in the seismic design codes at home and abroad, and demonstrated the effectiveness and practicability of different site classification methods.
(1) Site classification of strong vibration observation stations and statistical regression of ground motion attenuation relationship of different types of sites.
Based on 646 observation stations with complete drilling data and 25275 sets of ground motion records in the KiK-net network, the classification of observation stations and the grouping of strong vibration records were carried out according to six representative site classification schemes selected at home and abroad. The attenuation relationship between the peak acceleration and response spectrum of horizontal ground motion in different types of sites is given by statistical regression.
(2) The difference of ground motion in different types of sites and the consistency analysis of ground motion in the same type of sites.
The residual difference between the calculated value of the attenuation relation and the recorded value of the strong vibration is analyzed by using the statistical attenuation relation between the peak acceleration and acceleration response spectrum of different classified sites, and the consistency of the acceleration response spectrum recorded by the same type of site stations in the six site classification schemes is revealed, as well as the difference between the results of different site classification methods. The advantages and disadvantages of six site classification methods are discussed. The results show that the site classification of Chinese standard method is the most suitable way to characterize the influence of different site conditions on ground motion, followed by the site classification of Japanese standard method. The double index method using the thickness of the covering soil layer and the equivalent shear wave velocity of the soil layer in a certain depth range as the control parameters is the best method, especially the Chinese standard site classification method.
(3) Improvement of China's standard site classification method.
Considering the advantages and problems of Chinese standard site classification methods revealed above, two improved site classification methods based on equivalent shear wave velocity V Se30 with a calculated depth of less than 30m and overlay thickness are proposed.