| As the city development,the urban population increase sharply and to some extent lead to traffic congestion.The Xinhua News Agency issued by the national new urbanization planning(2014-2020),especially in strengthening the comprehensive transportation network.How to use a space reasonably become a prominent question of the urban planning.The subway is a new idea for the rational utilization of the space.Through the use of the underground space to build the rail transit and make up a three-dimensional structure with the ground traffic,effectively ease the pressure of the ground traffic and improve the efficiency.For providing the convenient traffic with the ground,the line of the subway is general along the road which has lots of the flyovers.So it inevitably traverses the existing bridges and the bearing capacity of pile foundation of a bridge is impacted.It is an important to study to establish a set of scientific management method that complete the subway construction on the premise of ensuring the safe operation of the existing bridges.Based on guan hui inter-city rail wear guangshen highway project as the engineering background.In the highway 120 km/h speed limit,do the upper structure jack-up,and tunnel excavation pile underpinning construction.In order to ensure the safety of bridge operation,analyzes the metro to wear under the bridge main risk factors,established an active protection management process having a comprehensive system of active defense and dynamic monitoring.It provides management experience and scientific management methods for a similar engineering.The main research:According to the traversing characteristics and the actual engineering,identification including the protective measures of construction risk,tunnel excavation construction risk and operation bridge risk,3 kinds of 12 risk factors,then set up a index system of construction risk of a subway traversing existing bridge construction risk.First,using FAHP and grey correlation method determine the index weight.Second,calculate the real cloud center of gravity and the most unfavorable cloud center of gravity,then in combination with the index weight,the results of comprehensive weighted deviation.Inputting the cloud model can get into the medium cloud cluster,belongs to level of risk.Analysis the traditional protection system shortcomings that is no guarantee the upper structure safety,put forward to active protection system on the premise of protect the safety of bridge operation,a comprehensive scientific prediction of risk,based on tunnel,formation,the structure of the bridge pile and the upper new type role relationship establish an active protection system.Then from three aspects of risk sources(tunnel excavation),risk carrier(deformation)and risk object(the pile,the upper structure),research protection principle,key points of protective methods and protective.of the traditional protective measures and the active protection measures.In view of the protection measures construction and the excavation construction,establish the dynamic control process,through the data reflect bridge state.The dynamic monitoring include monitoring objects,monitoring standards and arrangement of measuring points.According to engineering characteristics,the structure of active jack-up supporting pile and pile underpinning pile do settlement prediction and the results as a reference of a jack-up anticipation pile settlement reached the maximum.The active protection management system is established for a tunnel traversing existing bridges.Introduces the management system from risk identification and evaluation,to the use of protective measures,based on dynamic analysis of monitoring results to analysis of protective effect and launched the emergency management process adjustment.Included construction risk identification and evaluation,a comprehensive active protection system and dynamic monitoring.Three parts mutual cooperation,mutual support,closely related,not be short of one. |
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