Research On Low Temperature Cracking Mechanism And Prevention Measures Of Asphalt Pavement In Alpine Region

As the main disease of asphalt pavement in alpine region,low temperature cracking not only destroys the continuity and aesthetics of pavement,but also causes water seepage along cracks.Under the action of freeze-thaw cycle,it produces diseases such as looseness,mesh cracking and subsidence.More serious,it will soften the base,cause the decline of bearing capacity of pavement and reduce the service life of pavement.The low temperature cracking of asphalt pavement in alpine region is influenced by many factors,such as pavement structure,material,external environment,cooling and so on.Especially,the phenomenon of pavement cracking and destruction caused by the arrival of cold wave in alpine region is very common in a short time,which makes the causes of the cracking more complex.However,most of the existing studies focus on the effect of non-Alpine region or temperature cycle on pavement fatigue cracking.There is no consideration of the cooling effect of cold wave or cold current in the special climatic conditions of alpine regions.Therefore,it is necessary to study the mechanism and prevention measures of low temperature cracking of asphalt pavement in alpine region,which can provide theoretical basis and reference for the structural design,material selection and prevention of low temperature cracking of asphalt pavement in alpine region,and has important practical engineering application value.(1)Analysis of environmental characteristics and typical pavement diseases in alpine region.Based on literature review and meteorological data of China Meteorological Data Network,the geo-climatic characteristics,pavement structure and materials,typical types of pavement diseases and their causes in alpine regions represented by Tibet were investigated and analyzed,which laid a foundation for the establishment of temperature field and temperature stress model.(2)Establishment of low temperature cracking analysis model for asphalt pavement in alpine region.In ABAQUS modeling process,calculation model,analysis condition,pavement structure and material parameters,initial temperature field of pavement and determination of boundary conditions are discussed.Thereby,temperature field and temperature stress analysis model of asphalt pavement in alpine region is established.(3)Analysis of low temperature cracking mechanism of asphalt pavement in alpine region.Based on the analysis of influencing factors of low temperature cracking of asphalt pavement in alpine region,the influence of pavement structure,material and environmental factors on temperature field and thermal stress of asphalt pavement during cooling process is analyzed to reveal the mechanism of low temperature cracking of asphalt pavement in alpine region.(4)Study on prevention and cure measures of low temperature cracking of asphalt pavement in alpine region.Based on the low temperature bending test of trabecula,the effects of AC-13,SMA-13 gradation,base asphalt,SBS modified asphalt,rubber asphalt and polyester fiber on low temperature cracking resistance of asphalt mixture were studied.The prevention measures of low temperature cracking of asphalt pavement in alpine region were given from the aspects of material selection,structural design and construction control.