Seismic Response Analysis Of Coral Reef

Seismic response analysis of sea areas is the research direction in recent years.Because of the continuous construction of coral reef project in the South China Sea,the study of Coral Reef Site disaster prevention is imperative for minimizing the economic losses caused by the earthquake and the security crisis of national defense.Estimation of design parameters of coral reef engineering requires the understanding of surface ground motion parameters after response to soil layers.In this paper,the characteristics of seismic response around coral reef site are studied,and the main research contents and conclusions are as follows:1.The research status of engineering geology of coral reef and the influence of site conditions on seismic response are summarized.And the zoning of seismic intensity and the seismic geological structure of the South China Sea are introduced.2.The calculation method of soil layer response is frequency domain equivalent linearization wave analysis method,and soil layer response is calculated by using one-dimensional soil site seismic response analysis software DEEPSOIL.The present research status of engineering geology of coral reef at home and abroad is indicated: The coral reef site is mainly composed of calcareous sand and coral debris,the particles are hard and easy to break,and there is no weak interlayer,and the shear wave velocity of each layer has no regular change with the increase of depth.Refer to the coral reef field drilling parameters measured,physical and mechanical parameters including the thickness,depth,density,shear wave velocity and complex stress conditions of saturated calcareous sand under dynamic characteristics experimental study obtained shear modulus ratio and damping ratio curve of G/Gmax gamma lambda gamma curve,soil profile model is established for one-dimensional coral reef the seismic analysis required.3.Records of submarine ground motions recorded at 6 stations located 900m-2339 m below sea level in the coastal area of Japan's peninsula total are selected.According to the different depth of the hypocentral,the ground motion records are classified into shallow source seismic and deep source seismic.The ground motion acceleration(PGA),the ground acceleration response spectrum,the characteristic cycle,the response spectrum ratio are analyzed under the sets of ground motions.On site amplification the research results show that the amplification of coral reef site under deep epicentre ground motion is greater than the other groups.4.According to the energy holding time calculation method,select a large number of ground motion records these 5%-95% energy holding time greater than 140 s of East Japan earthquake.The ground motion acceleration(PGA),the ground acceleration response spectrum,the characteristic cycle,the response spectrum ratio and the ground motion time are analyzed under the sets of ground motions.5.A large number of near-fault pulsed ground motion records are selected as the strong earthquake database for bedrock inpu.The ground motion parameters obtained by the above earth seismic response are analyzed.The characteristic period of the ground acceleration response spectrum is closely related to the depth of the source,the duration of the earthquake and the structure of the site soil;The peak ground acceleration(PGA)of coral reefs is not affected greatly by the type of input ground motion,and is greatly affected by site soil layer structure.