Study On The Risk Assessment Method Of Underground Excavation Of Large Section Station Of Qingdao Metro

As an important national coastal city,Qingdao began planning for the construction of subways in 1987,and subway stations are an important part of subways.this article is based on the dangerous events that have occurred during the excavation of the Qingdao Metro large-section station and the actual site inspections.It is based on the methods of integrating theory with practice,comprehensive analysis combined with key analysis,experience summary combined with scientific inference,qualitative analysis combined with quantitative analysis.Starting from the difficulties faced by the actual construction status of Qingdao Metro's large-section stations and the hidden dangers existing in the construction itself,the aim is to construct a scientific and safety risk assessment index system,and to study the risk assessment methods applicable to high-risk engineering types in order to be precise to evaluate and measure the risk of underground excavation of large-section subway stations.The research contents and conclusions are as follows:(1)By studying the theory of construction safety risk assessment,it lays the theoretical foundation for the research content.By conducting a macro analysis of the risk characteristics of the underground excavation construction of the Qingdao Metro largesection station,it paves the way for the research of risk identification methods.(2)In-depth analysis and summary of the exploration process of the underground excavation construction method of Qingdao Metro large-section station,which is suitable for the Qingdao large-section construction method,the characteristics of the construction method,and the characteristics of construction risks;Based on the Qingdao geology belongs to the "upper soft and lower hard" strata,the geographical location is offshore and the construction environment is complex and changeable.The theoretical analysis of the high-risk and special features of the excavation construction of Qingdao Metro's largesection stations;Based on the monitoring data and the later-stage dangerous situation treatment measures,the dangerous events that have occurred in the large section of Qingdao Metro are researched,and the monitoring data characterization,cause mechanism,general potential risk sources,and corresponding treatment measures of different dangerous situations are analyzed and summarized;Through inspections and investigations on the construction sites of several large sections in Qingdao,in-depth analysis and summary of the general potential sources of risk in combination with the occurrence of dangerous events.(3)By analyzing the statistical results of on-site dangerous events that have occurred in Qingdao Metro,the characterization of monitoring data of large-section dangerous events,on-site inspections and investigations,relevant data and specifications,summarizes the risk factors involved in the construction of large-section underground excavation of Qingdao Metro,and then the risk nature is classified into five major areas,which are: construction's own risks,surrounding environmental risks,natural and geological risks,management risks,and social risks.According to the analysis of the characteristics of risks after classification,the WBS-RBS coupling matrix method can be better applied to risk identification.(4)The combination of subjective weighting method AHP method and objective weighting method entropy value method is constructed based on the combination weighting theory of game theory,and the index weighting method of safety risk factors suitable for the excavation of large-section stations in Qingdao Metro is obtained;By analyzing the gray system theory,using the improved multi-level gray clustering risk assessment method to evaluate the risk probability P and risk loss C of the risk constituents of the evaluated object,Finally,determine the risk according to R(28)P?C.(5)Through the questionnaire of relative importance of the risk factor indicators and the questionnaire of risk probability and risk loss,the “investigation method of on-site risk factor value” is proposed and applied in practical engineering cases to obtain the weights and engineering of risk factors.The actual risk size lays the foundation.Taking a large-section of Qingdao Metro Line 1 as a case to verify the content of this paper,and comparatively analyze the results of other assessment methods for the risk assessment of the project,highlighting the practical significance of this study.