Research On Key Construction Technology And Safety Control Of Highway Under-crossing Existing Operating Railway

With the continuous promotion of the density of our national highway and railwaynetworks, the cross between this two means of transportation has gradually increased.The highway under-crossing existing operating railway engineering means theconstruction of new cross between highway and existing railway needs to be completedby measures under the condition of normal operation of existing railway. Suchengineering has the features of general highway and its own particularity. Theprominent contradiction is the conflict between the safety of highway constructionregion and safe operation of existing railway line. On the one hand, the sub-grade ofrailway line will be affected and safety accident will happen during the construction ofnew highway under-crossing existing railway; on the other hand, the normal operationof existing railway lines under construction conditions will threaten the safety ofrailway operation. Especially during the highway box bridge jacking construction underthe existing railway, the sub-grade of existing railway and operation safety of train willcertainly be affected; meanwhile, the dynamic load of train when it passes theconstruction section will certainly affect the jacking construction. However, what’s thedegree of the mutual influence, how to take measures to protect the affected stratum andsurrounding environment and how to select the appropriate speed limits of box bridgejacking and train and precipitation plan to meet safe operation and ensure smoothcrossing construction have always been concerns of people. The paper combines thepractices of Shang-Zhou Phase Ⅱ engineering of highway box bridge under-crossingjacking Longhai Railway and Beijing-Kowloon Railway engineering and systematicallycollects the data of similar engineering and related researches to the following research:(1) Research the technical principle, scope of application and technological process of box bridge under-crossing jacking construction of highway-railway cross;(2) Put forward that the deformation of railway sub-grade during the jackingconstruction and surface gathered water on box bridge under-crossing section during theoperation period are main causes for the security risk in the highway-railway cross;(3) Use the software of finite difference FLAC3D and software of finite elementanalysis ABAQUS for numerical analysis of excavation of working pit, step length ofbox bridge jacking, train speed per hour and construction precipitation;(4) Put forward a railway sub-grade strengthening scheme according to the analysisresults and measures to control the deformation of railway sub-grade during the boxbridge under-crossing construction.(5) Put forward a solution of highway normal drainage+catchpit+seepage wellfor the problem of ponding on the highway under-crossing railway section of plain area;(6) Research the security risk management and control system of box bridgeunder-crossing construction: analyze main sources of danger and security risk factorsaffecting the construction through the research on specific and key constructiontechnologies and determine the index system of security risk assessment.The paper further researches the security risk management and control system ofbox bridge under-crossing construction through the analysis of key technology affectingsecurity: analyze main sources of danger and security risk factors affecting theconstruction through the research on specific and key construction technologies anddetermine the index system of security risk assessment of highway under-crossingexisting operating railway engineering; select a reasonable model of security riskassessment, collect corresponding data, evaluate construction safety of the engineering,provide reference for security management and decision of the project and put forward aset of improved safety management system for the highway under-crossing existingoperating railway engineering through comparison of various methods of security riskassessment.