Reasearch On Dynamic Monitoring And Early Warning System Of Metro Engineering Contruction Schedule Based On BIM

In view of the development trend of the increasingly large construction scale and more and more complicated construction procedures in the field of subway construction.the problems of insufficient management timeliness and incomplete data sharing mechanism in the traditional construction management mode have become more obvious.First,the key technologies have been deeply studied,such as construction schedule management technology based on critical chain,monitoring technology based on target tracking and three-dimensional laser scanning,and construction data management technology based on BIM standards.Furthermore,the dynamic monitoring and early warning system based on BIM for subway construction progress has been developed to realize the monitoring and early warning of subway construction progress and provide information,digital,and visual management.The main research results of this paper are as follows.(1)The construction progress monitoring algorithm of subway engineering based on the improved critical chain is constructed.The problem of subway construction schedule management is transformed into a project scheduling problem that satisfies both timing constraints and resource constraints,based on the concept of risk aggregation.And the critical chain identification algorithm for resource-constrained parallel scheduling and timing constraint conversion is constructed to improve the identification of critical chains.At the same time,by setting the insert position strategy of the critical chain buffer,the buffer calculation model consisting of initial buffer determination and initial buffer correction is established to optimize the calculation of buffer size.Furthermore,by assigning different weights to the two situations of task completion and buffer consumption,the buffer monitoring model of non-uniform consumption is established,which improves the execution efficiency of progress monitoring.Finally,an example is used to verify the adaptability of the algorithm under resource constraints and process interaction.(2)The BIM-based dynamic monitoring and tracking and early warning model of subway construction progress is establishedAccording to the dynamic early warning requirements of the progress of subway construction activities,the early warning problems are broken down into real-time monitoring of critical chain procedures and timely early warning of construction progress exceeding limits.In the progress monitoring stage,it is constructed that a deep learning critical chain process tracking algorithm based on construction site scenes composed of enhanced group trackers,depth detectors,and weighted P-N learning to solve the problem of difficult tracking of construction activities in the complex construction scene environment of subway projects;In the progress warning stage,the target tracking result is associated with the project BIM entity for automated monitoring,and the buffer consumption threshold analysis strategy is constructed based on the completion of the critical chain process activities.Through the combination of fixed monitoring,dynamic monitoring and BIM model,the process activity monitoring point setting and progress alarm display method are optimized to improve the visual effect of early warning.(3)The management and expression method of subway construction data based on IFC standard is proposedAiming at the management problem of structured,semi-structured and unstructured BIM data composition during the construction period of subway projects,it is put forward the BIM data storage mode combining relational database and XML file and the multi-type data access method associated with BIM model ID and file path.At the same time,it abstractly summarizes and matches the IFC standard entities based on the elements of construction activities.The construction activity information model based on IFC,the organization entity information model and the expression method of entity information model are constructed to improve the efficiency of information communication.And it is verified the consistency of the construction information expression method with the project site activities through concrete subway station examples.(4)The BIM-based dynamic monitoring and early warning system of subway construction progress is developed.In order to achieve efficient subway construction progress monitoring and early warning,the overall framework of a BIM-based subway construction progress dynamic early warning system was constructed.The system process and specific functions composed of the BIM data extraction module,the progress monitoring module,and the early warning response module have been sorted out,and the Microsoft SQL server relational database is adopted to establish the data association relationship between the BIM model component ID code and the progress monitoring data to achieve Dynamic coupling of BIM model and monitoring information.At the same time,in accordance with the data collection requirements,the point cloud data obtained by the 3D laser scanning is subjected to data de-drying and data simplification.After the mesh components and surface are reconstructed through parameter transformation,the imported system is compared with the original BIM model to obtain model differences and highlights.For the abnormal part of the building,complete the automatic collection of information and data on the construction progress of the subway project.(5)The BIM-based dynamic monitoring and early warning system of subway construction progress is verified by examplesBy taking a domestic subway station as an example,the engineering background of the case station project was analyzed,and the influencing factors of the station's schedule management and the requirements of schedule management and key monitoring procedures were clarified.And on the basis of subdividing the SX station construction plan,the improved critical chain model is used to obtain the process time of the SX station after considering the safety time,and the overall schedule project buffer and inflow buffer are set.Finally,by associating the BIM model component ID with each buffer of the critical chain,the information of completing the buffer monitoring points and milestone tasks is coupled in the early warning system to identify that the FB3 buffer reaches the early warning conditions and highlight the management staff to complete the early warning response.The rationality of this dynamic early warning method and the effectiveness of the early warning system are discussed.