The Study On Cumulative Damage Method Of Asphalt Pavement Based On Temperature Field

In order to make a more accurate reflect of the damage in pavement that is under alternative load and temperature effect,the design method of asphalt pavement design should be developed from equivalent damage method to cumulative damage method.Therefore,the dynamic evolution analysis of asphalt pavement mechanical behavior and the calculation of cumulative damage are carried out by the results of layered elastic physical calculation theory,dynamic parameters testing of pavement materials and measurement of axial load spectrum.First of all,based on the evolution of temperature field,the theoretical framework of asphalt pavement mechanics analysis is constructed,and the corresponding algorithm is perfected.Based on the real-time dynamic monitoring results of the temperature field,the dynamic evolution calculation of the mechanical parameters of the pavement material,such as the asphalt mixture in the typical area,is completed,and the variation range of the dynamic modulus of the asphalt mixture is demonstrated.Based on the dynamic temperature field,the dynamic evolution analysis program of mechanical behavior of asphalt pavement is compiled on the basis of the theory of layered elastic system,and the calculation accuracy and efficiency are ensured through the corresponding test.Further,based on the dynamic evolution analysis,the cumulative damage calculation program for asphalt pavement is written on the basis of the linear damage superposition principle,based on the fatigue of the stable base class,the fatigue the permanent deformation of the asphalt layer as the index.In the calculation program of pavement mechanics,the suitable scheme of pavement structure level division and temperature field sampling frequency is demonstrated respectively,and the scale,thus efficiency and accuracy of mechanical calculation are taken into consideration.Secondly,the dynamic evolution analysis of the mechanical behavior of asphalt pavement is carried out based on the mechanical calculation program of linear elastic layered system.The daily,monthly and seasonal analysis of dynamic response of asphalt pavement mechanical response is carried out by using the measured data of temperature field,which makes the calculation of cumulative damage based on temperature field basic feasible.Then the effect of load type on dynamic evolution is analyzed.The results show that the load type determines the tensile stress and shear stress at all levels of the pavement,and affects the spatial distribution of shear stress.Thirdly,the cumulative damage calculation procedure and analysis of asphalt pavement structure are completed.Using the layered elastic system program,combined with the results of temperature field monitoring,semi-rigid base fatigue model,asphalt surface fatigue damage model and asphalt mixture permanent deformation model,the cumulative damage calculation program of various pavement dzamage is written.The daily and monthly distribution characteristics of fatigue,permanent deformation of asphalt layer and fatigue damage of asphalt layer are analyzed,and the influence of load type,axial load spectrum and structure combination on the damage evolution is demonstrated.Finally,the dynamic evolution and cumulative damage of asphalt pavement in typical regions of China are analyzed.Based on the actual detection results of temperature field,the dynamic evolution rules of the same pavement structure in different highway natural zoning are compared.Then the base fatigue,surface fatigue and permanent deformation damage factors of pavement base are analyzed with time,and the unfavorable months of fatigue,surface fatigue and permanent deformation of surface layer are determined.The results show that there are significant differences in each region.It is proved that the daily distribution and annual distribution of the axial load spectrum have great influence on the damage.The structural combination and material design should be paid enough attention to.With the results of integrating temperature field,main curve of dynamic asphalt mixture modulus and random axle load spectrum are obtained,The dynamic mechanics evolution analysis and cumulative damage calculation program of asphalt pavement can provide support for asphalt pavement structure combination design and thickness calculation,thus further enriching and completing the design theory of asphalt pavement in China.