Safety Risk Assessment Of Shield Tunneling Construction For Dalian Metro Line 5

With the vigorous development of subway construction,tunnel shield construction technology has been widely used.Due to the complexity of subway tunnel construction,the diversity of influencing factors,and the seriousness of accidents,there are certain safety risks in subway construction.In order to study the safety problems affecting the subway shield construction in the coastal karst area and ensure the safe and efficient completion of the subway project,the research on safety risk assessment was carried out based on the tunnel shield construction project of Dalian Metro Line 5.The specific contents are as follows.(1)According to the characteristics of subway shield construction,WBS(Work Breakdown Structure)was applied to different construction stages,which were divided into 6 phases including pre-preparation of shield and auxiliary equipment construction,shield machine installation,shield lanuching,shield excavation,shield arrival,and shield crossing the special area.With the use of Risk Breakdown Structure(RBS),the risk factors were disassemble into 8 aspects,including personnel,material,machinery,technology,geology,climate,hydrology,and surrounding construction."WBS-RBS" coupled matrix was built,and the 121 risk factors were identified,forming a list of initial risk factors.(2)On the basis of the list of initial risk factors,the influence degree of each risk factor was scored by questionnaire survey.In addition,the reliability analysis and validity analysis were used for verification and adjustment,together with Program SPSS23.0,risk factors were filtrated,recombined and simplified.A total of 22 key risk indicators were filtrated,and the final risk list was completed,providing the foundation for the construction of risk evaluation index system.(3)According to the key risk indicators,risk evaluation index system was built,and the risk evaluation model was established based on principal component analysis-fuzzy comprehensive evaluation method.The risk matrix method was adopted to determine the risk level of each indicator.Finally,seven major risk indicators affecting the construction safety of the subway shield were extracted,and risk decisions were made,providing an effective reference for the shield construction of the Dalian Metro Line 5.