Design Of Drainage Deck Pavement Of Yuxihe Bridge And Its Durability Evaluation

Drainage pavement can drain off the water on the road and reduce spray and water drift,thus contributes to the traffic safety.However,the porous asphalt concrete is weaker than traditional dense asphalt concrete in strength.There is only limited study on the design & evaluation methods of porous asphalt concrete and limited examples of being used as deck pavement.This paper focuses on Yuxihe Bridge,which,with a complex stress state,requires excellent performance of the deck pavement.By the methods of field investigation,finite element software calculating and labotary testing,this paper studies the deck pavement of Yuxihe Bridge systematically.First,the application of drainage pavement both domestic and abroad is studied and the research content and technical route are proposed based on the stucture and climat of Yuxihe Bridge.This paper makes an investigation into the reasons of the damage of deck pavement and puts forward suggestions for avoiding these damage.Then,the stress state of the pavement is analyzed using a finite element software.Thus the worst load position is located.Through the finite element simulation calculation,the effects of pavement modulus,thickness,bond layer modulus,thickness and load on the stress state of pavement are obtained..Based on the rusults and the gradation design method studied,the material for the deck pavement is designed.As for the waterproof and cohesive layer,several kinds of materials are tested and rubber asphalt is selected for this research.Because the porous asphalt concrete is vulnerable to water,laboratory tests are conducted to studied the incluence of freeze-thaw and salt erosion.Specimen go through freeze-thaw cycles in water,industrial salt solution or environmental-friendly snow-melting chemical,after which they are tested to measure the decay of strength,durability and fatigue property.It is concluded that,as the specimen goes through more freeze-thaw cycles,its properties continue to decay.Moreover,salterosion mainly occurs at the initial stage when salt solution gets into the mixture.And salt erosion has greater impact on the fatigue property than freeze-thaw.It is confirmed that the environmental-friendly snow-melting chemical contributes to the protection of porous asphalt concrete.Finally,after the construction was finished,a field investigation is made and technical details are summarized.Through field measurement,the permiability coefficient is 1258ml/15 s,and compared with dense graded pavement,it can reduce the noise by 4.1 dB to 6.4 dB,which proves that the design is capable of drainage and noise-reduction therefore the pavement has great ecological benefits.