Study On The Identification And Assessmet Of Safety Risk In Shield Construction Of Crossing-river Tunnel

With the development of economic,the scale of cities in China enlarge constantly.The ground traffic in cities becomes crowded.The development of underground space has become an urgent need.As a quiet and efficient transport tool,subway has become the first choice for the development and utilization of underground space in major cities.However,in China,the development history of urban subway is relatively short,with relatively few reference experiences,and the construction of urban subway in major cities has entered a high tide period.In the construction process of urban subway,many safety accidents have occurred.The lesson of the tragic accidents warns that it's necessary to identify and control the safety risk resource in shield construction of crossing-river shield tunnel.The research purpose of this dissertation is to establish the identification model of safety risk resource in shield construction of crossing-river shield tunnel.The major contents of this dissertation are as follows:Work breakdown structure(WBS)and risk breakdown structure(RBS)of the shield construction in crossing-river tunnel are obtained.Shield construction can be divided into four construction stages:shield launching,shield tunneling,shield arrival and connection construction.The risk of Shield construction can be divided into three parts:mechanical equipment,construction method and environment.WBS-RBS method is used for risk identification,and then the identification model of risk source is established.Focused on the risk source of shield construction in crossing-river tunnel,the evaluation criteria of the probability of risk factors occurring during shield tunneling of crossing-river tunnel and its loss are established.Using the risk matrix method,the evaluation criteria of risk level are established.By means of expert investigation,the probability of risk factors occurring during shield tunneling of crossing-river tunnel and its loss are marked,the risk level of each risk factor is established,and then the major risk sources are determined.Taking Nanning rail traffic line 3 project(Keyuan road to Pingle road)as a case,the risk identification and its control measures carried out to validate the theoretical studies.