Research On Subway Construction Crown Beam Support Shaft Power Monitoring System

With the development of urbanization, the scale of the city subway has entered a stage of vigorous development, and the deep excavation of metro construction is also increasing. In the process of deep foundation construction, the stability of the envelope structure becomes extremely important. Metro crown beam support axial force is seen as the main parameters of the evaluation of structural health foundation pit, and its monitoring is a n important means to ensure that the supporting force does not exceed components capacity and ensure the safety of the excavation. In our country, support axial force monitoring applications is not a long time, and which monitoring mainly exists the problems that low level of the automation level is still low and monitoring axial force may be influenced by temperature and environmental impact is larger than the design value.To solve these problems, based on the existed research and design, relying on the Chengdu Metro Line 4 Phase II project, this paper takes the metro crown beam support axial force as the research object, and designs the axial force monitoring system for the whole. At the same time, the design of the power supply systems and data management system are studied in detail, combined with the support shaft power monitor factors affecting axial force values were analyzed. The main work is as follows:Firstly, considering the complexity and security of the power supply environment for metro construction site, a solar photovoltaic maximum power point tracking(MPPT) controller are designed. The design finally achieves the maximum power point of the whole system stable output, which is based on the design of improved voltage perturb & observe algorit hm. Experiments proved that the tracking efficiency of solar photovoltaic power generation controller can be up to 95%, compared to non-MPPT controller tracking efficiency by 19%, and has the advantages of a smaller size, lower cost, higher tracking effici ency and higher reliability. The battery equipment has been successfully used in the monitoring system and improves the system of long-term monitoring.Secondly, this paper use QT platform to design for a remote data management software. Based on the GSM network to achieve a stable data transmission, a data analysis and data display modules are set up. At the same time, based on My SQL platform, monitoring database platform is established. The database can unify different communication format to store data and provide query, add, delete and other functions, ultimately realize the control system communication, monitoring site management, data analysis and pro cessing, database maintenance and other tasks.Finally, combined with the support axial forces influencing factors, this paper analyzes the monitoring data and discusses the temperature compensation coefficient presumption. The calculation of support axial force with temperature correction falls nearly 20%, which effectively removed the support axial force monitor value larger phenomenon caused by temperature changes. At the end, we predict the support axial force by standard Kalman filter and adaptive Kalm an filtering algorithm. The results show that the absolute error of adaptive Kalman filter results is less than 12% and closer to the actual value, so that the method has some theoretical guidance in concrete support axial force prediction technology.