Study On The Influence Of The Pile Foundation Of Existing Bridge Caused By Underground Embankment Construction

Recentaly,our country's transportation network is improving day by day.It will be more popularly that new roads need to under cross existing road bridges,the under crossing construction of new way should be completed when the existed bridge under normal operation.How degree of the construct will affect the adjacent bridge and how to choose a reasonable construction and protection plan to reduce the impact to safe level has become the most concerned question.Therefore,on the one hand,it is necessary to study the influence of filling new roadbed on existing bridge's foundation and piers.on the other hand,control the pier movement and settlement caused by embankment load,is also have great practical significance.In this paper,based on the construction of the new road-Huichuan Road undercrossing the existing bridge-Ma longping Bridge of Lanhai high way in Guizhou Province.Use theoretical analysis,numerical calculation and field testing to study the influence of subgrade construction on bridge pier.The main works as follows:?1?Combine with engineering examples,anasys the stress characteristics of bridge piers and piles under different load conditions,established the differential equation of piles based on the winkler foundation model.Evaluate the project based on theoretical calculation,which shows that the offset of the 6#pier's pile top along the bridge is exceed the safety range,protective measures should be taken.?2?According to the actual situation on site,decidede to add a retaining wall located on soil surface near no.6 bridge pier.The design results show that the existence of retaining wall can effectively reduce the influence of embankment on the near pier.?3?Use FLAC^3D software establish the analytical model simulate the site construction process,obtain the influence law of bridge pier and pile foundation under roadbed filling process,draw conclusions:The displacement of bridge piers opposite direction with the embankment stack which increases with the increase of filling height,the maximum displacement along the bridge is no.6 pier,which is 5.3mm not surplass the safe range of10mm when the filling is finished.The construction of new way doesn't have much effect on the displacement vertical the bridge,which is under the range of-0.45mm to 0.45mm.The maximum settlement is located at no.4 bridge pier,namely the middle line of the road,the settlement is 4mm.?4?Analyze the monitoring data,obtain that:?1?The maximum excursion of bridge pier on no.6#pier is 5.4mm without exceeding the safety range.The construction of new way doesn't have much effect on the vertical bridge direction displacement,which is under the range of-0.45mm to 0.45mm.The maximum settlement is 4.2mm located at no.4bridge pier.?2?Made numerical simulation results comparing with field monitoring data,the reliability of the numerical simulation results is verified by the small difference.