Research On Risk Level And Early-warning Mechanism Of Concrete Faced Rockfill Dam Under The Earthquake

With the development of hydropower energy,CFRDs(concrete faced rockfill dams)are widely used in China because of its strong adaptability,economy,safety and other advantages.Most of these dams are located in the western region of China where strong earthquakes occur frequently.Once an accident occurs,it will cause inestimable losses.Therefore,the safety management of earth-rock dams under the earthquake has been concerned by the engineering field.As an extension of dam safety management,research on risk level and risk early warning mechanism of earth-rock dam under the earthquake,mainly includes identification of seismic failure modes,calculation of dam failure probability,classification of risk levels,construction of early warning mechanism and formulation of emergency response measures,etc.Therefore,this study can provide theoretical basis and technical support for seismic design,seismic risk assessment and seismic risk decision of CFRD and other earth-rock dams in meizoseismal area of China.Firstly,based on the actual seismic experience and related research of earth-rock dams at home and abroad,in this paper,the seismic failure modes of earth-rock dam were summarized and analyzed.And it was found that the dam deformation and the instability of the dam slope are the most common among all seismic failure modes of earth-rock dam.Secondly,In this paper,the failure probability of CFRD was studied based on two seismic failure modes:dam body deformation and dam slope instability.Dam cracks are used as the basis for judging dam seismic deformation failure,and dam seismic inclination is used as seismic safety index.The inclination method and center point method were used to analyze the dam body deformation reliability.The limit equilibrium method and ratio of safety margin method were used to analyze the dam slope stability.Based on these two common failure modes,the analysis method of seismic failure probability of CFRD is established.The proposed method is employed to calculate the annual seismic failure probability of Zipingpu CFRD during its design reference period.Thirdly,according to the related research of the predecessors,the risk loss assessment method was analyzed in detail from life,economy,social and environment.Based on the CFRD seismic failure probability calculation method,combined with the F-N risk standard curve and the ALARP criteria,the assessment criteria for the possibility of risk occurrence and the severity of risk loss were formulated,and the seismic risk level matrix was drawn.The risk is divided into 4 levels:?,?,?,? to evaluate its seismic risk level,so as to provide reference for the dam seismic design,seismic risk control and the establishment of earthquake risk early warning mechanism.And the seismic risk evaluation criterion was used to analyze the seismic risk level of Zipingpu CFRD.Finally,in this paper,the basic concept,purpose and principle of dam seismic risk early warning are summarized.And based on the 3D structure diagram of the early warning system,the seismic risk early warning mechanism was preliminarily constructed.Combined with the seismic risk level of CFRD,the evaluation standard of the seismic early warning level and the division of the seismic early warning level were established,and the emergency response measures of dam seismic risk are discussed.