Study On Asphalt Pavement Material Composing And Structure Design For The Permafrost Area

Road building in permafrost area is regarded as a difficult problem in the world at all times. For many special employing and constructing conditions of the highway pavement in permafrost area, pavement materials and structure should provide many special performances to adapt. In this thesis, the author systemically study on the asphalt pavement design technology of the permafrost area from the material and the structure.By the simulating test of the cement-stabilized gravel mixture, the characteristics under the low-temperature condition, such as the strength, shrink and anti-freeze, are studied. The critical dividing temperature that the maintaining temperature influences to the strength forming is firstly confirmed. The shrink worst status and the feasible anti-freeze evaluate method are recommended. Synthesizing the analysis results, the mix design method is put forward.On the basis of analyzing the strength forming and the settling process of the graded crushed rock, the author considers the essence of the plastic settlement to be the shear settlement between the grains. The settlements resist capability is systematically analyzed using the flexible material shear performance testing apparatus that invent by the author. According to the CBR and the shear testing results of the graded crushed rock, the key sieve pores and their reasonable passage range are recommended, the mix composing design method based on the CBR and the shear strength is brought forward.Through the low-temperature chrematistics testing and analyzing of the asphalt treated macadam, the integrative evaluating method of the low-temperature anti-crack performance that take the temperature stress ratio and the bending strain energy as the primary index. The mix design method based on the strength and the Marshell index for the asphalt treated macadam is developed.The effects of varies factors on low-temperature performances of the asphalt mixture are analyzed by the low-temperature performance testing. The influence of the hot-aging to the low-temperature anti-crack performance of the surface asphalt mixture is especially studied. Based on the mixture low-temperature performance, the mix design method is put forward.Based on the analysis of the thaw settlement of the frost roadbed, the influence of the roadbed uneven settlement on the asphalt pavement structure is quantitative analyzed, and the calculating method of the additive stress arise from the uneven thaw settlement in pavement structure is firstly given. Aiming at the peculiarity of the asphalt pavement in the permafrost area, the asphalt pavement structure design method found on the integrative effect of the loading and the thaw settlement is brought forward. Taking the traffic, the maximum thaw-settlement depth and the earth modulus as the controlling index, the recommended asphalt pavement structure is presented to the permafrost area.