Study On Performance Characteristics Of Graded Crushed Stone In Cold Region

The graded gravel base layer is a typical flexible base layer,which can effectively prevent the reflection cracks compared with the semi-rigid base layer.The Qinghai-Tibet Plateau belongs to the alpine high altitude area,and the traditional cement stabilized gravel base layer is more serious.In this paper,the mechanical properties of graded crushed stone are further studied,and the application of graded gravel base in the construction of highway pavement in high altitude and high altitude is of great practical and theoretical significance.Firstly,the disease research was carried out on G214 national highway,G109 national highway and S308 national highway.At the same time carried out the region of the grading of raw materials to investigate the nature of the work.The results show that the pavement reflection cracking caused by the traditional cement stabilized macadam base layer is more serious.In addition,the region of gravel raw materials with low density,high mud content,high water absorption,low strength characteristics.On the basis of this,five typical representative gradations were selected according to the actual application of the construction of large expressway engineering.The CBR,springback modulus and plastic deformation of graded macadam were studied.The results show that CBR increases with the increase of dry density,and the CBR decreases 8.3% after saturation.The modulus of elasticity of graded crushed increases with the increase of axial pressure and loading.The plastic deformation is divided into linear growth stage and springback stage,The loading times and axial compressions have a great influence on the plastic deformation.The confining pressure of graded macadam is linearly related to horizontal strain at 54 kpa ~ 94 kpa.The skeleton compact structure has a high CBR,a resilient modulus and a lower plastic deformation and Volume expansion rate should be limited under 0.9%.In addition,the shape and edges of aggregates have a significant effect on CBR and plastic deformation,and the effect on the elastic modulus is not significant.Taking into account the Qinghai-Tibet Plateau more rain and snow,cold weather and the larger temperature difference,further developed the permeability and frost resistance research.The results show that the graded macromolecule has a good water permeability,and the volume expansion rate is 1.28%.After 10 freeze-thaw damage,the maximum decrease of CBR is 63.6%.Finally,the construction technology and quality control method of graded crushed stone are analyzed by combining pavement of graded gravel base test section of Huadao expressway.