| In recent years,my country’s Prestressed Concrete Cylinder Pipe(PCCP)has developed rapidly.As of 2021,my country’s PCCP water pipeline operating mileage has ranked first in the world.The pipeline relocation project involves complex existing structure-soil interaction issues.Repeated disturbance of the pipeline foundation pit excavation can easily cause excessive deformation of the existing PCCP pipeline,and the structural deformation of the PCCP pipeline is required to be high during the service period.And the sensitivity of the socket to be affected by external forces is correspondingly increased,and a little carelessness will cause structural damage.In view of this,this article takes a PCCP pipeline relocation project of Guangzhou-Foshan-Zhaoqing Expressway as the background,and uses MIDAS GTS/NX and ABAQUS finite element software as the simulation platform to study the influence of pipeline relocation and renovation construction on the deformation of existing PCCP pipelines and control measures.Discuss the size and change law of the force required to pull out the pipe head and the installation of new steel pipes in the process of splitting and connecting,prevent possible dangerous factors,and provide a certain reference for the construction of similar projects.The research content and conclusions of this article are as follows:(1)A systematic investigation has been carried out on the relevant documents of PCCP pipeline relocation projects at home and abroad.Mainly summarized and analyzed the methods and results of domestic and foreign pipeline relocation projects and PCCP pipeline research,focused on the unreasonable places,and discussed,optimized and perfected the unreasonable places,and finally formed the research ideas and methods of this article.(2)The MIDAS finite element software was used to simulate the pipeline relocation and reconstruction process,and the mechanics response law of the pipeline foundation pit excavation and backfilling process to the existing PCCP pipeline was studied.Discuss the influence law of PCCP pipeline stopping and resuming water supply on existing PCCP pipeline.Research indicates:As the excavation of the foundation pit progresses,the displacement of the existing PCCP pipeline gradually increases,with a maximum value of17.73mm;as the backfilling of the foundation pit progresses,the displacement of the PCCP pipeline gradually decreases;stopping and restoring the water supply causes the deformation of the PCCP pipeline Within the controllable range,it will not affect the subsequent pipeline splitting and connection construction.(3)Research on the influence of the removal of steel sheet piles,supports,and construction of new steel sheet piles on existing PCCP pipelines during the construction of pipeline foundation pits.The results show that the removal of steel sheet piles,supports,and construction of new steel sheet piles have a significant impact on existing PCCP structures.This has a certain impact on the existing PCCP pipeline,but does not affect the split connection of subsequent pipelines.(4)Using ABAQUS finite element software to establish a refined PCCP pipe model,the drawing force required to pull out the old PCCP pipe head and the installation force required to install the new steel pipe and the PCCP pipe were studied.The trend of the displacement law during the exit process is approximately in the inverted "U" shape,while the trend of the displacement law in the installation process is approximately the "M" shape.In addition,it is recommended that the installation force required to install new steel pipes and PCCP pipes is maintained in the range of 35 k N～44k N,and it is recommended to maintain the required pulling force when pulling out the old pipe head within the range of 28.5k N～35.9k N to ensure PCCP.The normal use of the pipeline.(5)In-depth study using numerical simulation method,through the use of large-scale finite element software to establish a refined model of the pipeline,based on the different friction coefficients of the socket and the rubber ring during installation and extraction,Discussed the change rule of the pull-down force and installation force with different friction coefficients with the moving distance of the socket.It also reveals the relationship between the coefficient of friction and the pull-out force and installation force. |
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