Research For Damages Mechanism And Strengthening Of U-shaped Gravity Abutments

U-shaped gravity bridge abutment is a very classical abutment type, extensivelyapplicated in bridge design. The U-shaped gravity abutment resists the external force byits own gravity mainly. The force mechanism of the U-shaped gravity abutment is verycomplex. Under the action of the gravity load, the vehicle load, the soil pressure and so on,the structural damages occur, such as, the abutment cracking and the uneven subsidence ofthe abutment foundation, some abutments are badly damaged and seriously affecting theirnormal use. So, the strengthening and maintenance for U-shaped gravity abutments arevery necessary.The paper first analyzed the stress mechanism and summarized the mian damagestype of the U-shaped gravity abutments, then analyzed the main causes for the damages.Afte this, the paper studied three series of U-shaped gravity abutment, they are,(1)explore how the abutment height can influence the force of the abutment when the widthkeeps the same.(2) study the space force effect of the abutment with different width butthe same height.(3) analyze the influence to the stress of the abutment under different soilmoisture content when both the abutment height and abutment width keep no changing.Through studying these three series of U-shaped gravity abutments, the changing trend ofthe abutment stress and displacement with the changing of the abutment width, theabutment height and the soil moisture content are get.Based on the analysis of the damages causes, the paper proposed different methodsfor strengthening the U-shaped gravity abutments, including the anchor strengtheningmethod, the steel strand strengthening method, the reinforced concrete circle beamstrengthening method, the chamfer strengthening method and the foundation groutingstrengthening method. The stress and displacement of the U-shaped gravity abutment before and after strengthening and the reinforcement effect are studied using the ANSYSsoft ware.