Research Of Continuous Curved Bridge On Causation Analysis And Key Construction Technology For Deviation Rectification

With the construction of large-scale bridge projects in China,the level of bridge construction in China has made rapid progress,However,the bridge industry is also faced with long-term reconstruction,light maintenance and insufficient cognition of maintenance,repair and reinforcement of existing bridges,which makes many bridge projects face lots of thorny problems to be solved for a long time,among which the most representative is more and more bridge deflection problems.Based on the actual bridge rectification project in the coastal area,through numerical simulation and field construction exploration,research on the causes of bridge deviation,new bridge rectification technology and construction key technology,new bridge rectification process monitoring technology,etc.is carried out to ensure the safety and efficiency of continuous bridge rectification,especially continuous curved bridge rectification.The main research contents are as follows:(1)Using the general finite element program GTS NX and Midas civil,the whole numerical simulation model of bridge and soil is established to calculation and analysis the influence of the upper box girder load(Constant load,second stage constant load,overall temperature rise and fall,local temperature rise and fall,vehicle eccentric load,etc.)and the lower pier load(balanced soil load,unbalanced soil load)on the bridge deviation.Through comparative to the actual Bridge dislocation,it can be concluded that the main reason for bridge deviation is the unbalanced soil loading of the lower pier,and the technical idea of unloading the unbalanced soil in the region first,and then rectifying the bridge deviation is put forward.(2)Through the calculation of the bearing capacity and the maximum crack width of the underground hidden pile foundation of the lower pier,the bearing capacity of the lower pier pile foundation from the seventh to the eleventh joint meets the safety requirements and has a certain safety margin.Except that the maximum crack width of 35 th pier pile foundation is 0.27 mm,which is exceeding the specification limit,the concrete crack checking calculation of other pier pile foundation less than 0.2mm,which meets the specification requirements.the repair treatment of the pier with large damage should be carried out before the rectification construction.For the damage of hidden pile foundation of the existing bridge without the detection pipe embedded in advance,it is proposed to use the side hole transmission wave detection technology for damage detection,which has been proved to be feasible.(3)In view of the large deviation of the bridge after the soil unloading,the integral rectification method of the upper box girder rectification is proposed,which is the combination of the jacking at the expansion joint and the jacking at the pier top.The jacking force of the horizontal jack at the pier top is mainly used to overcome the friction between the upper box girder and the temporary sliding surface.The horizontal jack at the expansion joint is mainly used to push the upper box girder to move longitudinally.For the upper continuous box girder with consolidated pier or limited support pier,the construction method that the upper box girder can be corrected in place together with the correction of more than one pier is put forward,and the key construction technology for the correction of continuous straight box girder and continuous curve box girder is defined according to the correction construction process of the upper box girder.(4)According to the difficulty degree and stress state of the rectification of the lower pier,the two-stage dynamic rectification concept is put forward.In the first stage of rectifying the deviation of the lower pier,the jacking method of the lower pier is mainly used,with the help of the technical means such as the excavation of bearing platform soil,the drilling of soil stress dissipation holes,etc.,to realize the rectification and restoration of the lower pier.Using the jacking rectification technology,the most dislocation of the pier can be effectively solved.In view of the situation that the first stage cannot achieve the rectification of the lower pier,the second stage pier rectification technology is proposed by using the combination of the middle pull of the cushion cap and the top push of the pier.According to the rectification construction process of the lower pier,the key technology of the second stage rectification construction of the lower pier is defined.(5)By using the general finite element program Abques and Midas civil,the simulation analysis of bridge deflection correction construction process is established,and the bearing reaction acting on the top of the pier and the control limit value of the first stage deflection correction top thrust after overcoming the friction are determined.the method of trial jacking is proposed to determine the friction between the pier support and the temporary sliding surface,and the friction coefficient of the friction test and the friction calculated by the reaction force of the support are compared,which verifies the scientificity of the proposed method,and the friction between the pier support and the temporary sliding surface determined by the method of trial jacking after the first stage of overcoming the friction control limit value and the method of trial jacking The sum of the two is determined as the control limit of actual construction jacking force.At the same time,through the study of the corresponding relationship between the concrete strain increment at the unfavorable position of the pier column and the hidden pile foundation,the control limit of the concrete strain increment at the monitoring section of the lower pier is determined.(6)In view of the rectification construction of the upper continuous curved box girder and the rectification construction of the lower pier by jacking,using the long-term engineering practice experience accumulated in the past bridge rectification construction,the monitoring index and new monitoring technology research of the rectification construction of the deflection bridge engineering,especially the concealed works of the lower pier,are carried out,and through the analysis of the monitoring results of the rectification construction of the bridge,which is beneficial to guide the actual bridge rectification construction.