Research On Safety Risk Early Warning Of Subway Construction Based On Cloud Model

With the continuous development of the urbanization process,the pressure of urban space capacity is increasing,and the massive population inflow leads to the increasingly severe urban traffic situation.In order to alleviate the pressure of urban traffic,many large and medium-sized cities have built large-scale subway.By 2019,40 cities in China have or are under construction subway,and the national subway has been approved with a planned mileage of 6118.8 km.The acceleration of subway construction speed,coupled with the construction geological conditions and the complexity of the surrounding environment,lead to frequent subway construction safety accidents.Compared with other subway construction,the environment is worse,the construction technology is more complex,the construction management on site is more difficult and there are many hidden dangers.These characteristics lead to more complex risk factors and serious consequences of safety accidents in subway construction,which brings new challenges to subway construction safety management and early warning.In addition,the traditional subway construction safety early-warning method is difficult to effectively solve the fuzzy random uncertainty of early-warning indicators.Therefore,this paper uses the cloud model and D-S evidence theory to effectively solve the fuzzy random uncertainty of early-warning indicators and other advantages,and discusses the subway construction safety risk early-warning topic from multiple perspectives and levels.The following work has been completed:This paper first collects 247 subway construction safety accidents in 2003-2017,takes this as the research object and analyzes the accident law,including the three aspects of accident city distribution,time distribution and type distribution,analyzes the risk factors of 247 subway construction safety accidents by using the subway construction safety accident cause theory,and combines the subway construction early warning Content and process: from the perspective of human,machine,environment,management and structure,construct the early warning index system of subway construction safety risk,and divide the index into two categories: safety risk monitoring index and safety risk inspection index.The inspection index includes four first-class indexes of human,machine,environment and management,and 45 second-class indexes.The monitoring index constructs 19 first-class indexes for station foundation pit and tunnel Indicators and corresponding secondary indicators.Then,based on the research status quo of subway construction safety risk early warning and cloud model,this paper points out that there are few researches on subway construction safety risk early warning using cloud model at present,compares the common methods of subway construction safety risk early warning,and points out that these methods are difficult to solve the problem of fuzzy random uncertainty of evaluation index when they are used for construction safety risk early warning;this paper discusses theoretically Cloud model and D-S evidence theory can naturally solve the fuzzy random uncertainty of evaluation index.Then through the historical experience,relevant system standards and engineering experience to determine the threshold value of early warning indicators,and divide the warning limit of each warning level of early warning indicators,that is,early warning standard cloud.The index weight is determined by the combination of AHP and entropy weight.The cloud model and D-S evidence theory are used to calculate the digital characteristics(normal cloud model),index data consistency,dimensionless processing and multi-level comprehensive early warning of the cloud.The human,machine,environment and management in the patrol index are selected from the heavy,medium and light alarm states The early warning index of safety accident is used to determine the early warning level of safety accident and send out the corresponding level alarm.A complete early warning model of subway construction safety risk based on cloud model is constructed,which can be used to early warn the construction safety risk level of actual subway project.Finally,taking Wuhan Metro Line 7 as an example,this paper uses the early warning model of subway construction safety risk established in this paper to carry out case analysis.The results of case analysis show that the second level indicators of the first level indicators of subway construction management,safety production inspection and reasonable site layout risk factors are in the "middle alarm",the other indicators are in the "light alarm",and there is no "heavy alarm" indicator;In the first level index early warning,there are no "medium alarm" and "heavy alarm".Finally,the overall early warning result of Wuhan Metro Line 7 is "light alarm".Finally,combined with the early warning result,the early warning control measures of subway construction safety risk are preliminarily discussed.The establishment of early warning model of subway construction safety risk based on cloud model can feed back the hidden danger of safety risk in the process of subway construction in time,make early warning of possible safety accidents in the process of subway construction,and provide scientific decision basis for adjusting subway construction scheme and emergency plan,so as to minimize the probability of safety accidents,casualties and environmental damage,To ensure the safe and orderly construction of urban subway project,it also provides a powerful scientific,systematic and intelligent safety risk management tool for subway construction.