Research On Key Technologies In Construction Monitoring Of Short-line Precast Segmental Cantilever Erection Bridge

With the rapid development of bridge structure,short-line precast segmental cantilever erection bridge are widely used.The bridge sturcture’s quality is effectively improved,while the construction efficiency is enhanced due to the application of short-line precast segmental cantilever erection method.Basing on Yueqing Bay Bridge,this paper discussed key technologies in construction monitoring of short-line precast segmental cantilever erection bridge.Literature data,finite element theory,finite element model,construction monitoring operation were used in the research process.The results are presented as follows:1、Technologies in construction monitoring of short-line precast stage are summarized.Error formula of horizontal deviation of the target tower relative to the measuring tower is derived.For every 30 meters long girders with ten segments,9.9 millimeters error can be caused by a deviation of 3 millimeters.Four-point Spacing Control System which apply to short line method on soft soil foundation is put forward.2、Technologies in construction monitoring of cantilever erection stage are summarized.Two new erection error adjustment ideas are put forward.By error calculating method,the reasonable range of Total Station Instrument Control System between the locating point and total station’s control point is proved less than 200 meters.3、As the deviation of the 3 control lines at each node is most in the range of 5mm,the linear control of short-line precast stage is proved to meet the accuracy requirements.The maximum deviation of cantilever erection stage is out of specification limits 25 mm.Considering no adjustment measures have been adopted,the linear control of cantilever erection stage is acceptable.The position of the T-frame beam group is limited by the segment of the pier.The position of the side span section beam group is limited by the position of the adjacent T-frame.4、The parameter sensitivity analysis results are presented as follows.The sensitivity of the uniform super square to the vertical displacement of the node is weak(super square 3%,average deviation is 1mm),to the production camber of node is strong(average change is more than 20%),to the bridge state stress is weak.The sensitivity of the half super square to the vertical displacement of the node is weak strong(super square 3%,maximum deviation is 5.7mm).The sensitivity of the segment stored period to displacement along the bridge of the node is,the production camber of node(average change is less than 10%),the bridge state stress is weak.The sensitivity of the prestressed steel pipe’s frictional coefficient(deviation coefficient)to displacement along the bridge of the node is,the production camber of node(average change is less than 10%),the bridge state stress is weak.The above research can provide some references for construction monitoring of the same type bridges.