Investigation On Mechanical Behavior Of Two Kinds Of The Abutment

As a common light abutment,pile pillar abutment has the advantages of good adaptability and energy conservation and environmental protection;Composite anchor plate abutment arose:in the 80s,boomed in the 90s,but later gradually declined due to the construction being complex and the quality being difficult to guarantee,however,because it can provide relatively large traffic space,helping to solve the problem of vehicle shunting in the traffic hub area,hence,in recent years,it has been gradually developed.But currently,these two kinds of the abutment not only lack of the systematic and in-depth investigation on the general stress distribution,but also the optimization investigation on the structural style,therefore,this paper selects the mechanical behavior of the two kinds of the abutment as the investigation object,adopts the numerical simulation in conjunction with:in-situ measurement as investigation approach,and make the general distribution of.the stress field and structural style optimization to be investigation content followed by the specific investigations:(1)Investigation on stress field.In order to study the behavior of pile pillar abutment and composite anchor plate abutment under the combinations of the dead load,vehicle load,trajBfic lane load,and soil pressure behind abutment,the three-dimensional nonlinear finite element numerical models whose grounds,foundations,and abutment structures are cooperative,are established under the six loading modes,the systematic and detailed distributions of stress field and displacement field are achieved,further the most disadvantageous loading mode and the abutment structure weak points are found out according to the comparative analyses,moreover,by the displacements of the composite anchor plate abutment being compared with the in-situ measurements,the numerical simulation rationality is validated.(2)Investigation on optimization.The wing wall of pile pillar abutment is changed from rectangle to trapezoid,the angle between the wing wall and the parados is changed from 135° to 180° and 90°,the comparative studies on the stress and displacement distributions of these several abutment styles are conducted,seeking mechanics modeling general rules of the both abutment structures and probing their optimizational structural style.The conclusions are:(1)The foundation soil should be treated with geo-stress balance;(2)Compared with the soil pressure behind abutment,the effect of vehicle load behind abutment on the stress and displacement of the abutment is relatively small,so it can be neglected;(3)The horizontal displacement of the composite anchor plate abutment is relatively small,this will help to solve the problem of vehicle pitch at the bridge end;(4)The parados and wing wall in the abutment comprise the space shell,and present the spacial cooperative work,while at present,the relevant codes separate them and take them as the single basic structural components to design one by one,this approach should be corrected;(5)It helps to improve the parados mechanical behavior as well as the stress of the abutment structure for the wing wall to bear the appropriate soil pressure,but it runs counter to its desire for the wing wall to bear too much soil pressure.It can acquire the optimizational structural style of the abutment to control the geometry of the wing wall and the angle to the parados for seeking the rational style of the spacial shell composed by the wing wall and parados;(6)The trapezoid wing wall of pile pillar abutment can effectively improve the stress state of the parados,so is the optimizational structural style of pile pillar abutm.ent;With respect to composite anchor plate abutment,the angle between the wing wall and parados is 135° and 180°,can improve the overall mechanical behavior of the abutment,so is the ideal structural style selection of composite anchor plate abutment.