Study On Seismic Effect Of Sedimentary Basin

Some previous large earthquakes indicate that the basin will obviously enlarge long period and increase the duration of strong ground motion, which will badly destroyed the high-rise buildings, the long-span bridges, and some other engineering structures with long vibration periods. In china, many large and medium-sized cities are located on the sedimentary basin, so the basin effect research is very important for the earthquake prevention and disaster reduction of these cities, and it is also very important for recognizing the effect of this large non-homogeneous site; moreover, promoting the development of the earthquake engineering. On the base of summarizing mass literatures both abroad and domestic, the main research works of this paper are as follows:1.Based on simple 2-D basin model, the influence of the dip angle, the depth and the impedance of basin on the surface wave generation, the edge and focusing effects under vertical incident the SH-wave are qualitatively studied. An estimated formula about the region and the amplification coefficient are given in this paper based on a great number of model analysis.2.Based on the geology and investigation data, the drilling and wave measurement data of Shidian basin, eight geologically profiles of the basin are detailed drawn, and a 3-D velocity model of Shidian basin is constructed in this paper. This model will provide a basis for basin effect research in our county.3.Used the above 3-D model of the Shidian basin, the long period ground motions under vertical incident are simulated by explicit finite element method combined with parallel computation, and the edge and focusing effect of this basin are studied. Five geological sections from the 3D model are extracted for 1-D, 2-D and 3-D contrast analysis and the results show that 3-D model calculation is larger than others.4.Three geologically profile of Tangshan are drawn, and a 3-D velocity model of Tangshan area is constructed in this paper based on the extensive drilling data in Tangshan area. The near field broad-band strong motions of the 1976 great Tangshan earthquake are numerical simulated, and the result are contrasted with the seismic intensity map of 1976 Tangshan earthquake.