Study On The Deflection Design Criteria System Of The Flexible Base Asphalt Pavement

Deflection on road surface is one of the most important control criteria in asphaltpavement design of our country,in order to meet the developments of road and traffic,thecriteria has been modified in different periods of road construction.Asphalt pavement withflexible base has high shear strength,flexural tensile strength and fatigue resistence,it canovercome some disadvantages of semi-rigid base pavement,has becoming main developmenttrend of high-grade highway.This article according to the problem of slightly larger deflectionappeared in the construction of flexible base asphalt pavement,analysed the characteristics ofhome and abroad asphalt pavement design,on this basis,study on asphalt pavement indexestake combination methods of field survey,regression analysis,mechanical cauculations andengineering example. This paper make the following achievements:1. Analysed the suitability of current asphalt design method,holds that the current designmethod is not suitable for fexible base asphalt pavement;the comparative analysis of homeand abroad design methods show that the criterial of our asphalt pavement design is toosimple and is difficult to control road diseases.2. Study on design deflection cauculation system,obtained the coefficient value ofstructure types that adapted to GuangDong Proveince flexible base pavements.3. Through mechanical cauculation methods,analysed the deflection and bottom layertensile stress of three different typical pavement structure. The analysis of road deflectionshowed that the flexible base pavement has the lowest strength.The research in bottom layertensile stress shows that the bearing model of flexible base pavement is very effective indelaying asphalt layer reflection crack and improving road working life.4. Support construction analysis.Demonstrates the feasibility of the modified designdeflection caulculation formula;comparatively analysis the deflection and bottom layer tensilestress results of different cauculation software(HPDS,ANSYS,BISAR),conclusion that ourdeflection control is too rigorous and tensile stress cauculation is slightly larger.