Research On Key Techniques Of Control Network Repetition And Construction Settlement Observation Of Extra Large Bridge

With the rapid development of China’s transportation industry,bridge construction has entered a new historical stage.Bridge construction control is an important work of bridge construction quality assurance.With the development of modern bridge to long distance,large span,high pier tower.and other new complex structure,precision requirements of bridge construction control network and the settlement observation are required to be continuously improved.Since large bridge construction control network repetition and stability evaluation methods of control points,optimization of control network repetition period,and the settlement observation of long-span bridge pier are very important works,the research and analysis on the related techniques are of essential necessity.Based on the under-construction project of Hutong Bridge,this paper focuses on the research about construction control network repetition and settlement observation method.The main content of the work and conclusions are as follows:1)Introduction to the technical method and technical problems of the construction control network establishment of the super large bridge and analysis on the technology of construction control network layout of Hutong Bridge as well as the technical requirements and the result of the position surveying of primary control network.2)Introduction to several basis of reference standards and selection requirements of construction control network.Research about three methods of stability analysis of construction control network:the Mean Spacing Method,Spacing Block Method and T-test method,improvement to the conventional mean spacing method--to decompose the displacement into displacement of X direction and Y direction,and then to analyze the stability independently and findings based on the Hutong Bridge construction control network:in terms of stability analysis for the horizontal control network,distinguishing unstable point reliability of the improved mean spacing method is better than the conventional mean spacing method.3)Research on the relationship among measurement precision,repetition period and point displacement of the control network,the newly raised calculation method of control network repetition period and proves of the fact that this method can reduce the blindness of the control network repetition and make the determination of the control network repetition period more scientific according to the real example of Hutong Bridge project and data analysis.4)Study on a applicable and high precision leveling method of pier large span,its appliance to the project of Hutong Bridge for the water bridge pier settlement monitoring and results:settlement observation of synchronize trigonometric leveling method in short distance(less than 1000m)of the cross river leveling is feasible,the measuring precision is better than standard requirements,and the work efficiency is also greatly improved.