Study On Crack Mechanism And Reinforcement Of U-shaped Abutment In Mountainous Area

In order to improve the level of traffic and promote regional economic development,it is necessary to do a good job in the construction of traffic engineering in mountainous areas.At present,the traffic engineering in the western mountainous area of China is in the peak period of construction,among which there is no lack of a large number of bridge engineering,and the abutment is mostly gravity U-shaped abutment.According to relevant statistics,during the construction and operation of bridge in mountainous area,U-shaped abutment cracking phenomenon often appears.In this thesis,theoretical analysis combined with finite element numerical simulation is used to study the crack mechanism and reinforcement method of abutment structure.The main research works completed in this thesis are as follows:(1)According to the different loading conditions of the abutment in the construction period and the operation period of the bridge,two loading conditions of the U-shaped abutment are set.Through the theoretical analysis of the abutment force and the finite element numerical simulation analysis based on ABAQUS software,the dangerous loading conditions of the abutment are compared and established.(2)In the numerical simulation analysis and evaluation of the abutment,four "characteristic parameters" are used to represent the stress and deformation of the U-shaped abutment.Based on the finite element numerical simulation analysis of abutment with different widths and heights under dangerous working conditions,the characteristic parameter values are summarized and the cracking mechanism of abutment structure is analyzed and expounded by combining the theoretical analysis results.(3)Considering that the forces and constraints of the front wall and the side wall are not the same,the non-45 ° chamfering design scheme is adopted for the new abutment.The U-shaped abutment with different width and height was modeled and analyzed under the reinforcement of various chamfering cutting dimensions,and compared with the conventional45° chamfered abutment.The optimization effects of different schemes in the design of chamfered abutment were quantitatively evaluated through the value of characteristic parameters.(4)The reinforcement effects of different acting positions of anchor cables in the tensile reinforcement scheme are compared and studied,and the optimal acting positions of anchor cables are preliminarily determined.According to the variation law of the maximum stress of the step body with different anchor cable tension,the concept of "ultimate tension" in anchor cable pair tension reinforcement is put forward,and the reinforcement effect of various characteristic indexes under the condition of "ultimate tension" is analyzed.In this thesis,two more suitable reinforcement schemes of anchor cable are put forward for the wide split-seam abutment,the relationship between the ultimate tension and the size of the abutment is studied,and the reinforcement effects of various characteristic parameters are summarized.(5)Other abutment structures and foundation reinforcement methods are introduced,and measures and suggestions for abutment cracking prevention are provided.