Research On Construction Monitoring Technology Of Long-Span Railway Low Tower Cable-Stayed Bridge

In recent years,with the promotion of China's comprehensive national strength,public transportation has entered a period of vigorous development and the high speed railway is even known as the country's weight.At the same time,bridges are important nodes to across rivers,lakes and the sea in the traffic line and its quantity,quality and speed of construction are constantly refreshing the original records.The prestressed concrete low tower cable-stayed bridge,with the advantages of its stiffness and span,and the beautiful shape,is more and more adopted in the railway line.However,the construction process of the low tower cable-stayed bridge is complex,and the interaction between cables and beams is obvious.In order to ensure the safety of bridge in the construction process and the internal force and the line shape after completion can meet the design requirements,it needs to be monitored throughout the construction.It is of great practical significance to study the construction monitoring technology of the long-span prestressed concrete low tower cable-stayed bridge.This paper introduces the domestic and overseas development situation of the low tower cable-stayed bridge,and the origin and research situation of the bridge construction monitoring technology firstly,defines the purpose and content of the bridge construction monitoring and summarizes the commonly used monitoring methods.As the subject of study,the Panzhihua Jinsha River bridge of the modification works of the Cheng-Kun railway is discussed in matters of its main problems in the process of construction monitoring,and the related experience is summarized.The finite element model of the Panzhihua Jinsha River bridge is established for the theoretical calculation of the bridge by using Midas/Civil,and parameter sensitivity of this bridge is analyzed by using the model.Taking the main influence parameters and combining the measured data,the parameters of the model are corrected by using the least square method.According to the characteristics of different construction stages,different construction monitoring methods will be applied to suitable stages.In the early stage,due to the difficulty of parameter correction,the prediction monitoring method is applied,and the parameter correction is applied to the monitoring system in the later stage.At last,the construction monitoring results of this bridge are compared and analyzed,and the main dividing line shape,stress and cable force are expounded in three parts.In addition,in the mid-term of the bridge construction monitoring practice,the construction sequence and the control target are changed specially at the same time.In this paper,according to the difference of the degree of influence,the linear control measures are given for the change of the construction sequence and the change of the control target.For the most influential cases,a method of making use of the minimum residual sum of squares fitting of the compromise line shape is proposed to make the line shape of the new control target guarantee the smoothness and its error keep at a lower level at the same time,It can provide certain ideas for similar problems.