Research On The Safety Risk Assessment Of The Newly-built Subway Station Closely Pasting Underneath The Existing Operating Station

The metro station is one of the most important infrastructures of the metro system.Underground transfer metro station is the joint of many lines,and it is the heart of the metro system.With the large-scale construction of urban railway transportation,the crossing and transfer problems of various lines will be produced,and thus many node stations will be developed,resulting in the metro tunnel running through the existing tunnel or metro station.Currently,the existing metro tunnel or metro station project under the metro turnel is mainly studied,whereas there are few studies on the new metro station under the existing operating station project.Due to the particularity,complexity and high risk of this kind of project,the safety risk assessment of the new metro station closely pasted under the existing operating station project is performed,which contributes to related units to control the risk of similar projects.Based on relevant national standards,industry standards and actual engineering conditions,the safety risk assessment of the project of new metro station under the close stickers of existing operating stations is conducted as follows:(1)Firstly,the literature of typical construction cases and safety risk assessment theories at home and abroad are reasearched in this paper,and then a field survey on the construction site is conducted.The causal analysis method and Delphi method are adopted to identify the risks of the project of closely pasted undercrossing existing operating stations in the newly built metro stations,and the preliminary risk factor table is developed.(2)The entropy weight method was used to identify 49 key risk factor indicators for the 75 three-level indicators in the preliminary risk factor list.A security risk assessment system consisting of 2 first-level indicators,12 second-level indicators and 49 third-level indicators is obtained.The security risk assessment levels of each three-level indicators are classified into high-risk,medium-risk and low-risk,respectively.At the same time,the qualitative or quantitative rating criteria of the three-level indicators as well as the possible accident consequences after the occurrence of this risk are given.(3)According to the established safety risk assessment system,the questionnaire was set up and issued to 30 experts who participated in the construction of the newly-built metro station and underneath an existing station project.Firstly,the analytic hierarchy process is used to calculate the weight of related risks.Then,the fuzzy matter-element method is adopted to determine the classical domain and the node matter matrix.In addition,the correlation function and the degree of association are confirmed.Finally,the comprehensive correlation degree is calculated and the comprehensive evaluation level is determined to form the risk assessment result.Furthermore the corresponding countermeasures are given for the high risk factors.(4)A safety risk assessment on the Dongda Road Station Project of Phase I of Chengdu Metro Line 8 is conducted.According to the results of risk assessment,the corresponding countermeasures are given for the three relatively high risk factors.The research results provide a good theoretical basis for the safety risk assessment of the new metro station with close stickers.