| Earthquake liquefaction is a complicated natural phenomenon,which also causes great loss to human life and property.In particular,in recent major earthquakes,engineering damage and social disasters caused by liquefaction account for an increasing proportion,which has become a "cancer" in the earthquake protection and disaster reduction work and an extremely dangerous resource that may endanger human security.China is a country with high risk of earthquake liquefaction hazard.It is of great significance to study the theory and technology of earthquake liquefaction risk governance.At present,the system of liquefaction control technology used in engineering was formed in the 1960 s to 1980 s,and great progress has been made in the research of many specific technologies and methods.Up to now,seismic design based on risk,performance and resilience has become the development trend of earthquake disaster prevention,which also puts forward new requirements for governance of earthquake liquefaction hazard.Among them,it is necessary to develop and update the existing technical system of risk governance of earthquake liquefaction hazard with new ideas.Meanwhile,it is necessary to study the control factors and shortcomings of the technical system.According to the theoretical methods and latest progress of management,systems engineering,earthquake engineering,technology and other disciplines.this paper studies and establishes a new technology system for risk governance of earthquake liquefaction hazard aiming at the objective needs of technology development for risk governance of earthquake liquefaction hazard.The three control factors of the technology system,namely,the liquefaction fortification standard,the investment standard of liquefaction fortification,and the liquefaction risk assessment,were studied,and the shortcomings are seaeched and made up,in an attempt to provide scientific guidance and technical support for the development and application of risk governance of earthquake liquefaction hazard.The main work and achievements of this paper are as follows:1.The establishment of a new technology system for risk governance of earthquake liquefaction hazard is the primary task to ensure that the risk governance of earthquake liquefaction hazard.is carried out under the guidance of the ideas of risk,performance and resilience.Through systematic study,this paper summarizes the obvious characteristics of earthquake liquefaction damage in such aspects as the extensiveness of disaster-causing objects,the severity of disaster-causing consequences,the cascading of disaster-causing effects,the particularity of disaster-causing mechanism and the complexity of governance technology,and expounds the construction principle of technical system,pointed out the existing problems of the liquefaction governance technology system in our country.By fusion advanced risk management system in the commercial field,both the engineering risk management system and performance-based degion of earthquake engineering(PBDEE),the advantages of the comprehensive consideration of the sociality of the target,the integrity of the function,the hierarchy of the composition,the linkage of the elements and the completeness of the technology,this papper put forward the control objectives and connotation of risk governance of earthquake liquefaction hazard,set up a new technical framework and technical process of risk,performance and resilience for risk governance of earthquake liquefaction hazard framework and the technical process,to provide a guide and a route for control and coordination of research and technology development on risk governance of earthquake liquefaction hazard.2.The risk fortification standard of liquefaction hazard is the first control factor in the new technology system,and its importance as a component element of the governance target is beyond doubt.However,due to the lack of understanding of the difference of liquefaction hazard under different levels of ground motion in the past,there is a lack of unified standard and confusion in the liquefaction fortification of existing engineering construction in China.By using the new technology system,this paper compares the overall requirements of China’s engineering seismic fortification and liquefaction fortification standards,and have found the serious defect that the standard of liquefaction fortification in building,construction,highway,railway,water transportation and electric power widely used in China is not in conformity with the overall requirements of seismic fortification.Furthermore,through the theoretical analysis of risk difference if liquefaction hazard under different fortification levels and the earthquake damage investigation,it is proved that the current mainstream standard of liquefaction fortification will seriously underestimate the liquefaction and its damage extent under actual large earthquakes.It is pointed out that taking peak ground acceleration of large earthquakes as site liquefaction fortification value is an important problem to be improved in seismic code of main engineering field in China.On this basis,taking the overall requirements of fortification and the liquefaction risk as the control index,this paper proposes the recommended standard of liquefaction fortification for typical engineering,which makes up for the shortcomings of the existing seismic fortification standard.3.The investment standard of liquefaction fortification is the second control factor in the new technology system,and its importance as another component factor of risk governance goal is beyond doubt.However,there is little research in the past,which leads to blindness in the research and development of anti-liquefaction technology methods.Based on the extensive,representative and authoritative investigation,this paper analyzes and obtains the basic understanding of the acceptable ability of professional groups to invest in earthquake risk prevention and control in China,and puts forward the law of the influence of earthquake risk areas,the seismic classification of building and the fortification targets on earthquake investment decision-making.On this basis,taking the consensus formed by professional groups and the probability level of liquefaction as the control index,this paper proposes the investment recommendation standard for liquefaction fortification of typical construction projects,which makes up for the shortcomings of the existing seismic fortification standard.The results show that there is consistency in the ratio of seismic investment selected by professionals with different identities for key and standard fortification buildings in different seismic risk areas.The aseismic investment ratio selected by the authority group is regular for different aseismic classification buildings under the same fortification target.For similar buildings designed according to different fortification standards,the aseismic investment ratio selected by the authority group changes to a certain extent but is not significant.These results can provide guidance for the development of risk prevention technology of liquefaction hazard.4.Liquefaction risk evaluation is the third control factor in the new system.As a basic factor under the concept of risk,it is closely related to the formulation of the above two standards,and determines the enforceability of the new system as well as the control factor of all the technical methods in the new system.In this paper,the existing evaluation methods of liquefaction probability and their shortcomings are analyzed,a new evaluation model based on single variable is established with the systems engineering methodology,and a new calculation method and formula of the sand liquefaction probability are put forward by using the new model,and a large number of seismic data are compared and tested.The new method proposed in this paper,combines the more mature deterministic method of soil liquefaction determination with the classical mathematical method of probability solution,overcomes the shortcomings of the existing methods in deep soil,extendes the reasonable evaluation interval of liquefaction probability from 10 m underground to 30 m underground.The new probability evaluation method of liquefaction risk,gaves the guarantee the high quality of operation of the new technology system in the paper,and provides a new technical support for the liquefaction disaster risk assessment in China’s engineering construction with a large number of deep foundations and underground facilities. |
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