Shield Construction Of Metro Project Based On System Dynamics Progress Control Study

As China’s cities enter the peak period of subway construction,the shield tunnel construction method has also been applied more and more widely.How to prevent the progress of shield construction delay has become the main research direction of subway project management.This paper applies the system dynamics to the progress control research of the subway project.Based on theoretical research,literature research,case analysis and actual project investigation,the system dynamics modeling is carried out.Helps managers analyze the progress issues from an overall perspective and provide a reference for managers to make progress control decisions.The main research contents of this article are as follows:First,we review the related theories.The theory of subway shield construction is introduced.The concept of subway schedule control and the concept of system dynamics are introduced.The superiority of applying system dynamics to the progress control of metro projects and the modeling method based on system dynamics Vensim software are described.The establishment of the model laid the foundation.Secondly,according to the characteristics of the metro project,the system considers the main factors affecting the construction progress and the interaction mechanism,and establishes four subsystems: the construction process subsystem,the target duration subsystem,the human resource subsystem,and the shield mechanical influence factor subsystem..The speed of construction in the construction process subsystem was analyzed in detail,and the construction speed structure chart was drawn.The Delphi method and sequence relation analysis method were used to assign and weight the influencing factors of the shield machine,and the mechanical influence factor of the shield was obtained and calculated.The comprehensive influence coefficient of shield machine influence.According to the mutual relations among various subsystems,a system dynamics model of shield construction progress control for metro projects was established.Finally,taking the shield construction project of Chengdu Metro Line 1 as an example,the subway project progress control model was used for simulation study to verify the validity and rationality of the model.To plan the construction period as the goal,simulate the shield construction time and personnel changes curve,and give advice for the manager to make progress decision.On this basis,a simulation study was conducted on the schedule control strategy,which was the overtime strategy of shields,the influence degree of each factor of the shield machine,and the personnel strategy.The following conclusions were drawn:(1)In the early stage of the project,the overtime strategy of using shields is better than overtime.(2)The construction unit should give priority to improving the level of the four factors of uncovering the shield driving machine,blockage of the grouting pipeline,excessive height difference between the segments,and excessive rotation of the shield machine.(3)The completion time of rework is not proportional to the increase of personnel and overtime of personnel,and the increase of personnel over the period of time when the pressure of the schedule reaches a certain value is better than that of the increase of personnel during the early period of the project.Excessive overtime and increase of personnel will cause late-employment personnel to be idle.The corresponding strategies for personnel strategies should be simulated according to different strategies.Through the established dynamics model of the subway project schedule control system,a “simulation laboratory” for the subway project progress control system operation has been initially formed,which lays the foundation for the scenario analysis and research of the subway project schedule control system and is important for the progress management practice Value.