Study On Construction Monitoring And Numerical Simulation Of Steel Sheet Pile Supporting Structure For Bridge Cushion Cap Foundation Pit

With the rapid development of my country’s economy and the increase of urban population,the rapid development of highway and bridge construction has been promoted.Under the background of rapid development of bridge construction,the load on the superstructure of bridges has become larger and larger,which has brought difficulties to the construction of bridge foundation pits.It is a great challenge,and the bridge foundation pit project is also developing in the direction of deep,large and difficult.The design of the foundation pit project must not only ensure the strength and stability requirements of the foundation pit supporting structure,but also ensure that its deformation can be controlled within the specified range,that is,from the design stage of the bearing capacity limit state to the design stage of the normal service limit state..Foundation pit engineering is an interdisciplinary subject that spans mechanics,structure,geotechnical and engineering disciplines,and at the same time,foundation pit engineering support technology is highly practical and regional.Since deep foundation pit support is only a temporary construction measure for underground engineering construction,it has not received enough attention from construction units in the past,blindly saving costs,frequent accidents,and ultimately huge waste.In recent years,with the rapid development of national urban construction,the design,construction and monitoring technology of deep foundation pit support have also made great progress.People have begun to realize that deep foundation pits not only require the safety and stability of the foundation pit itself to ensure normal operation in the pit,but also control the movement of the foundation pit and the soil outside the pit to ensure the normal operation of buildings,roads and pipelines near the foundation pit.According to their specific conditions and combined with engineering practice,engineers and technicians in various places have carried out a large number of scientific researches and obtained a series of results.This paper will rely on the design review and construction monitoring project of the foundation pit of the south main tower of Nanjing Longtan Yangtze River Bridge,combined with the on-site engineering geological conditions(deep layered soft foundation)and the existing engineering facilities(bridge group pile foundation,gantry crane foundation)and levee protection piles),to analyze and study the construction monitoring and reasonable support methods of the deep foundation pit of the bridge caps near the embankment.Firstly,monitor the displacement and settlement around the foundation pit and at the building during the excavation process of the foundation pit,use Midas GTS NX software to analyze the parameters of the original support design scheme of the deep foundation pit,and cross-comparison with the monitoring data to study its changing laws.Using Midas GTS NX finite element analysis software again,the three-dimensional foundation pit modeling was carried out,and the design schemes were further compared,and the deformation law and characteristics of the combined support structure were analyzed.Numerical simulation and comparison of different design schemes were carried out,and different design schemes were synthesized;after comparing with the monitoring values,the characteristics and laws of the overall deformation of the foundation pit,the deformation of the supporting structure,and the internal force of the supporting structure were carried out through three-dimensional numerical simulation.This has laid a foundation for improving the design optimization of the combined row pile support structure of the foundation pit,and will ultimately improve the construction efficiency of the foundation pit.