Seismic Safety Assessment Of Gongzui Hydropower Station On Dadu River

Gongzui Hydropower Station on Dadu River is one of the first hydropower projects built after the founding of new China.The project was started in March 1966 and put into operation in 1978.Since 2002,it is planned to carry out the technical transformation of unit capacity increase,and the total capacity will be increased to 770 mw.It has been clearly stipulated in the first five-year economic plan that seismic fortification should be carried out for all important projects in earthquake areas.When the 1977 edition of "China seismic intensity zoning map" was officially issued and implemented,the project has been basically completed.The basic seismic intensity adopted by Gongzui Hydropower Station for seismic fortification under the condition of lack of seismic data is quite different from the current national seismic standard,which can not meet the requirements of engineering seismic safety evaluation.After the Wenchuan earthquake in 2008,the State Seismological Bureau,the national development and Reform Commission and other departments and stations have successively issued documents calling for strengthening the seismic design of hydropower projects.In order to ensure the seismic safety of Gongzui Hydropower Station and meet the requirements of unit capacity increase technical transformation,it is necessary to carry out the seismic safety evaluation of the project site.On the basis of fully collecting the research results of seismic safety evaluation in China,aiming at the analysis and evaluation of regional seismic tectonic environment,near-field and active structure in the field,the seismic risk probability method is used to analyze the vibration parameters of the engineering site under each probability,and the artificial bedrock acceleration time history of each probability is proposed to meet the dynamic analysis and static analysis of seismic design of hydraulic structures The need of force analysis.The main research contents are as follows:(1)based on the data of strong and weak earthquakes recorded by historical earthquakes in the region,the spatial distribution characteristics of regional seismicity are analyzed and the seismic zones are divided.This paper studies the regional seismic geological background,evaluates the regional seismic tectonic environment,elucidates the main tectonic conditions of strong earthquakes,and discusses the characteristics and activities of the main fault zones in the region.The characteristics of near-field seismicity and neotectonic movement are studied,and the characteristics of fault activity in near-field are discussed in detail.(2)on the basis of the research results of regional and near-field seismotectonic environment,the corresponding seismicity parameters are determined according to the principle and method of potential seismic source division.The attenuation relation of ground motion is obtained by using the method of transformation.By calculating the contribution of seismic zone to the seismic risk of each site,the seismic risk index of the site is calculated.(3)through the analysis of the site’s geographical position and geological structure,the design parameters of ground motion are determined,including the peak acceleration,response spectrum and time history.