Seismic Risk Analysis Based On Fine Grid Engineering Site And Earthquake Linkage

Earthquake is one of the major natural disasters in China.It not only causes huge economic losses,but also seriously threatens people’s life safety.Therefore,the prevention work in earthquake prone areas is very important.However,at present,science and technology can not accurately predict the occurrence of earthquakes,so it is impossible to reduce the impact of earthquake disasters through early warning.Seismic risk analysis can provide a theoretical basis for the seismic design of building structures in designated areas,so as to reduce the losses caused by earthquakes.Therefore,seismic risk analysis is one of the most effective methods to prevent seismic hazards.With the development of science and technology,seismic risk analysis methods are mainly divided into deterministic seismic risk analysis methods and probabilistic seismic risk analysis methods.Because of their respective advantages and disadvantages,the two analysis methods serve different types of engineering projects.For example,deterministic seismic risk analysis generally serves special projects such as nuclear power plants,while probabilistic seismic risk analysis mostly serves general civil buildings.In order to express the seismic risk more intuitively,the seismic zoning method is usually used in the research at home and abroad.However,the current seismic zoning map in China can only provide the maximum seismic intensity that may be encountered in a certain area(more than ten kilometers,square kilometers),and can not give more detailed seismic impact in the area.In this paper,based on the gridding of engineering sites and taking Chengdu as an example,a research method based on seismic linkage(simultaneous earthquakes in adjacent areas)is proposed on the basis of deterministic seismic risk research method and probabilistic seismic risk method.The main research contents are as follows:(1)Take Chengdu to 500 m × More fine meshing shall be carried out at a distance of500 m.Using historical seismic data and Monte Carlo random experiment,based on deterministic seismic risk analysis and probabilistic seismic risk analysis,and taking source distance,peak velocity and peak acceleration as parameters,the detailed seismic impact distribution in Chengdu is analyzed.Solve the problem that the current seismic zoning is not fine enough,and provide a strong theoretical basis for the seismic design of various types of engineering projects in Chengdu.(2)Improve the existing attenuation formula and increase the influence of simultaneous interpreting of different propagation media.In most studies at home and abroad,the seismic attenuation formula is calculated by epicentral distance,and mainly for earthquakes with epicentral distance less than 100 km,so the influence of propagation medium on seismic wave is ignored in the attenuation formula.Because the minimum seismic distance studied in this paper is about 10 km and the maximum is about 600 km,the influence of propagation medium can not be ignored.Therefore,in this paper,the source distance of the actual propagation path of seismic wave is selected as the influence parameter of distance,and the influence of medium is added into the existing attenuation formula of Chengdu,so as to make the calculation result more accurate.(3)A risk analysis method based on earthquake linkage is proposed.Firstly,assuming the linkage of historical earthquakes,the impact of earthquake linkage on Chengdu is studied by using the method of deterministic earthquake risk analysis,and the distribution of earthquake linkage impact in Chengdu is obtained.Compared with the influence distribution without considering the historical earthquake linkage,the results show that the risk of earthquake linkage is about 20% higher than that without linkage.Secondly,Monte Carlo random experiment is used to simulate the possible earthquakes in Chengdu in the next 50 years,and the linkage of future earthquakes is considered.The impact of earthquake linkage on Chengdu is studied,and the distribution of earthquake linkage impact in Chengdu is obtained.Compared with the impact distribution without considering the simulated earthquake linkage,it is finally concluded that the risk of earthquake linkage is about 20%-30% higher than that without linkage.The seismic belt around Chengdu is complex,the earthquake frequency is high,and there is earthquake linkage.The earthquake linkage will have a greater impact.The seismic linkage risk analysis is of great significance.