The Safety Risk Analysis Of Urban Subway Construction And Related Case Study

Urban rail transit projects need large investment, complex technology and high operational requirements and its construction involves a wide range of influence. Therefore, it is necessary to identify and evaluate risk standing in the perspective of project decision maker, to analysis of project overall risk level and to put forward the main risk response measures. The above is particularly important for the follow-up engineering design, construction and operational risk management.On the basis of the background of risk management theory,this paper has a systematic introduction of the theory about the risk of subway construction, according to the characteristics of subway construction risk and risk factors. And according to the definition of engineering risk,the formation mechanism of subway construction risk is described. Through its construction characteristics,the high risk and particularity of subway engineering is summed up,and the identification method and risk estimation method of major hazard sources are classified.Combining with the background of the first phase project of Guangzhou rail transit line fourteen, this paper firstly analyzes that there are six major risks in the hydrogeological condition. They are crack, karst, uneven weathering of bedrock,boulders, soft soil and residual soil. In the course of construction, the risk of foundation pit slope failure is moderate to large, the risk of land subsidence is moderate,the excavation slope stability risk is small to moderate,and the risk of ground collapse is moderate. Secondly,combining with the operation condition risk assessment method(LEC method),the risk assessment of the engineering construction method is carried out. The average value of the risk score D is 68.1. It belongs to the general risk level, in the acceptable range.Relying on Guangzhou rail transit line eight North Extension Project,through the analysis of the engineering geological unit,this paper studies the influence which bad geology and special rock and soil has on the risk of crack,karst,uneven weathering of bedrock, boulders and soft soil, and puts forward countermeasures. And then,laying mode,present situation along the line,line station and interval method,surrounding environment and security of line are carried out risk analysis. In order to ensure the security,the paper put forward the corresponding strategy. For duration risk analysis of external coordination conditions and internal cooperation construction schedule, it is concluded that duration could be ensured by taking the appropriate measures.