Research On Structured Mechanical Characteristics And Design Methodology For The Gravity Type U-shaped Abutment Under High Fill

Gravity type U-shaped abutment because its the advantages of convenient for construction and convenient materials is widely used in engineering,the height of the u-shaped abutment of the current standard drawing below 8 meters,width within 12 meters,it is difficult to meet the requirements of the practical design.According to a survey based on the existing and under construction abutment,has a mass of cracking phenomenon when fill height greater than 8 meters or width greater than 15 meters of the abutment,the integrity of the abutment was damaged.This article through the centrifugal model experiment,the finite element analysis simulation experiment and field engineering test,studied the high fill Gravity type U-shaped abutment body strain-stress rule that with different height,different width,different working conditions,to seek high fill Gravity type U-shaped abutment force characteristic,put forward the design method that makes the high fill abutment to prevent or alleviate crack disease and makes structure is more stable.Specific research contents and results are as follows:?Based on the analysis of a large number of information collection,analysis of the existing high fill Gravity type u-shaped abutment cracking phenomena in the process of construction and operation,summarize its reason.Concluded,the cracking reason is mainly:first,high fill abutment side wall and front wall cross section width isdifficult to meet the specification requirements,there is big limitation in the currentspecification.Second,the active earth pressure calculation is simplified to plane calculation,cannot really reflect the influence of the lateral earth pressure on wall body.?Analyzed the stress-strain distribution rule and its change increases with height step down the different heights.Centrifugal model test and finite element analysis simulation results validate each other,on the abutment body vertical compressive stress was small under large distribution,and increases with height,compressive stress increases as a whole.Transverse stress distribution,pull down on the side wall at the top of the free end as the tensile stress concentration area.?Analyzed the stress-strain distribution rule under different aspect ratio,narrow high abutment filling is smaller,filling weight is difficult to maintain the abutment stability;large number of filled soil made wide abutment's side and front wall produce large horizontal pressure,resulting in wall body deformation.Use the finite element analysis simulations and centrifugal model test results comparing centrifuge model,get the position of high fill abutment that is more easily to be damaged,crevice from intersection of side wall and front wall to middle in side wall:broken on side wall'bottom side;submerge phenomenon of foundation.?Analyzed under different working conditions the abutment body's stress-strain distribution.As the main bearing structure the front wall of gravity abutment is under vertical pressure,in the design and construction process should pay attention to throw of eccentric of the center of gravity and occurring topple under pressure.Especiall abutment has narrow high form,need to ensure the filling in the abutment is enough,in order to maintain body balance.In the operation,the greater the height of the abutment,the longer side walls,bottom and front wall acting on the free end of the sidewall restriction effect is smaller,which deform increasingly intensified,for the above conclusions construction that should pay attention in the construction.?Put forward high fill gravity type U-shaped abutment stepwise design method combine Structured mechanical characteristics of high fill gravity type U-shaped abutment.Through the finite element analysis,stepwise solution is suitable for the high height more than 25 meters,smaller width narrow bridge abutment,effectively solves the problems by filling smaller.?According to the finite element analysis and centrifugal model test of stress concentration and transaction failure position,combined with the existing gravity type U-shaped abutment reinforcement theory summarizes the application conditions and the advantages and disadvantages of.?Tests at the scene of construction project,Confirm the experiment of the stress-strain distribution rule each other.