The Study On Systematic Metro Projects Safety Evaluation Model Based On The Fuzzy Set Theory

With the prosperity and development of national economy, the construction of urban rail transit in our country has entered a rapid development stage. The use and construction of city metro can, to some extent, relieve current traffic pressure and promote the sustainable, rapid and sound development of national economy. However, because of high difficulty and high risk as well as limited safety management level, metro construction projects in China are facing frequent safety accidents. Therefore, a study on safety assessment and safety management at construction stage not only helps to improve safety management level and enhance the ability to control safety accidents, but also contributes to predict and reduce them during metro constructions, In this way, casualties and economic losses can be reduced to the lowest level, which ensures that metro constructions can be proceeded smoothly.In order to effectively solve safety management problems faced in present metro construction projects in our country, this article, involving an amalgamation of subjects like safety system engineering, management science and engineering, construction engineering, etc., puts forward a theoretical scheme and its specific operational method which is a comprehensive model of safety assessment for metro projects based on fuzzy set theory. This method accelerates the research and development of safety management in metro construction and is of great theoretical significance to future development of the comprehensive safety evaluation of metro projects in our country. The main work and study of this article are as follows:(1)First of all, this article analyses current situation and problems existing in safety management of metro projects. Also, it discusses and analyses recent researches of safety assessment both at home and abroad. The author holds the opinion that the recent researches of safety assessment stop at a level that is either qualitative or semiquantitative. Most methods are still limited to theories and local application, lacking systematic and scientific quantitative model. Therefore, it requires scholars in related fields to make further exploration and innovation.(2) The article statistics the causes of safety accidents and its regular. By means of summarizing the results of statistical analysis and researches of some other scholars and literatures, the author identifies the main factors which affect the metro project security level. These factors fall into four categories, namely, environmental factors, human factors, construction technology and equipment factors, and safety management factors. Based on the design principles of safety assessment index system, the author establishes the metro safety evaluation index system by selecting easily quantifiable and controllable factors that significantly impact metro projects. By utilizing the analytic hierarchy process and expert questionnaire survey, this article makes weight values assignments for all levels of the indicators in safety evaluation system of metro project.(3) Based on the fuzzy set theory, The article establishes the metro safety evaluation model which is based on the fuzzy set theory. It provides theoretical bases and scientific methods for the comprehensive safety evaluation of metro projects. The model scores all levels of evaluation index by using expert scoring method, and it makes a good use of arithmetic operator to get the operating safety evaluation matrix. And then the final results of the safety assessment is worked out by using muti-level fuzzy comprehensive evaluation method. With good feasibility, scientific and the rational evaluation process, and persuasive evaluation results, this method is able to effectively investigate the safety level of all aspects of the construction phase of metro projects, and it promotes construction companies to take timely and appropriate measures to avoid further safety incidents and damages.(4)Appling the metro project safety evaluation model which based on fuzzy set theory to Dalian metro project, the author demonstrates the metro project safety assessment model which based on fuzzy set theory is operational and scientific. According to the first and second levels of fuzzy systematic evaluation method, systematical analysis of the safety level of Dalian metro project is made which shows the safety level of Dalian metro is "qualified" and there is some possibilities for safety accidents. Low safety level of Dalian metro project mainly results from three reasons which are low level of construction technology, shortage of construction experience, and poor safety management. This article gives the corresponding countermeasures and suggestions to these issues which are enhancing the environmental monitoring in pre-construction and construction processes of metro project, introducing third-party security monitoring system, establishing a more robust emergency rescue system, and so on. A certain degree of subjectiveness in determining the weight and value in fuzzy comprehensive evaluation should be a shortage of this article. So there is still some room for further research.