Study On The Overlay Technique Of Asphalt Pavement

Nowadays, many domestic asphalt pavements are in the maintenance or wanting for maintenance. Highway design, construction and scientific research which focused on the new design and new road are transferring to the maintenance of the old road network. The transformation made the technology of asphalt overlay necessary. The technology has been studied by the expert all over the world, and some encouraging results have been obtained. However, in some aspects the researches are not substantially in-depth or systematical. With the financial aids of the national western transportation construction project which is called"the design of asphalt pavement overlay and construction technology"(item No.: 200531881213), based on the widely collecting and analyzing the relative information of asphalt overlay and combining with the specific circumstances of our existing overlay structure, further research of the methods and theories of asphalt overlay is done, in order to propose the feasible technology of asphalt overlay in accordance with the current national condition.This dissertation has mainly researched six aspects as follows: (1) Aiming at the inadequacies of existing comprehensive evaluation method, comprehensive evaluation of pavement performance based on the interval of approximation method is established for the first time. Considering the engineering requirements and the variation of roadway attribute, section of uniform disturbance method based on the cumulative difference is established. (2) In view of the question that the thickness of milling is difficult to control, the change rule of the deflection before and after milling have been analyzed, and the change law of the deflection before milling and the equivalent snapping back module after milling have been researched. The design criterion of the asphalt pavement based on the deflection control had been determined for the first time, which provides the basis for the determination of milling thickness and overlay design. The materials of tack coat, seal coat, seal coat, waterproof layer and so on have been studied, and the technology of interlaminar treatment has been proposed.(3) After systematically surveying of the typical asphalt overlay structure on 30 domestic highway asphalt pavements, the asphalt overlay structure and finite element calculation model has been established. The change rule of the asphalt overlay internal force under the axle and temperature load has been systematically studied, and the coupling stress of overlay is numerically analyzed by orthogonal design methods. Finally, the compression, shear stress and the temperature field between layers have been comprehensively analyzed, and the interlaminar condition has been established. (4) In view of the chaotic situation of the position of interlayer, through comprehensive analysis of the effect of position of interlayer on the overlay stress and strain, the optimum position of interlayer has been proposed from the three aspects of the anti-cracking ability, extending the fatigue life and improving shear cutting performance for the first time.(5) In the indoor ideal conditions, the relevant comparative tests of different grid interlayer of asphalt mixture and overlay structure have been done by using interlay shearing device, drawing machine, Marshall multi-functional strength device and rutting machine, and then the test results have been evaluated by a rational approach. Meanwhile, the simulated test of the overlay fatigue life has been done by using ordinary rutting machine, and the different overlay thickness of different grade interlayer and different sawing depth of overlay structure have been studied by the fatigue test.(6)The design method of overlay structure based on the residual life has been proposed. The design index of the asphalt overlay structure has been improved, and the fatigue axel load conversion factor of vertical shear and the interlaminar shear has been established. Meanwhile, optimization method of overlay structure based on DEA method has been established, which compensates the past deficiencies of optimization method.