Research On The Influence Of New Bridge Construction On Adjacent Existing Passenger Line Bridge

ABSTRACT:In recent years, the railway network intersection and compactness inevitably lead to the situation that a lot of new lines are cross or parallel with the existing lines. When the new bridge near the existing bridge is built, the construction processes including drilling pile construction, foundation excavation, bearing platform construction, the construction of bridge pier and girder erection all can cause negative impact on adjacent existing bridge. Based on the actual project in Wenzhou region, the research on influence of new bridge construction on nearby exsiting bridge is carried out including the following concrete contents and results:(1)Displacement of existing bridge and stress of surrounding soil were monitored. The actual project situation in Wenzhou region was discussed firstly.Combined with field situation, every process flow of new bridge construction was showed. The existing bridge risk from new bridge construction was qualitatively analysed, which indicated that monitoring to construction near existing bridge was necessary. Static leveling instrument and soil pressure sensor were used to monitor displacement and soil stress respectively. Measuring point arrangement, monitoring instrument installation and burying were emphasized. The effect of every process in new bridge construction on the existing bridge was researched through analysis of monitoring data.(2)The finite element simulation to the whole new bridge construction processes was established by Abaqus to study new bridge construction impact on the existing bridge vertical displacement, horizontal displacement and track geometry status. Stress variation of surrounding soil caused by the drilling pile construction was analyzed. According to variation of soil stress along the depth, the entire drilling process was divided into three characteristic stages. In addition, impact of new bridge construction in different drilling order on the existing bridge was studied using comparative analysis method.(3) The effect of moving trains on the existing bridge was researched. Soil vibration in new bridge construction area induced by running trains was measured. Soil disturbance in construction area induced by vibration was studied, and then impact on existing bridge was analyzed. Velocity and acceleration time history were deep researched for different partitions. At the same time, monitoring displacement data during trains running were also analyzed to further research effect of moving trains on the existing bridge.(4) Software which can be used to analyze vibration measured data was developed independently. The software function included data preprocessing, background vibration analysis, eigenvalue calculation, spectrum analysis, calculus operation and characteristic frequency extraction. The trend item of measured data was removed by using data preprocessing module. Peak, effective value, vertical Z vibration level and weighted horizontal vibration level of velocity and acceleration were calculated by using data analysis module. One-third octave spectrum analysis was discussed by using spectrum analysis module.(5) The measures to reduce the effect on existing bridge were discussed, and the new bridge construction monitoring methods were proposed.