Research On Dynamic Evolution Of Asphalt Pavement Stress State And Application Of Strength Theory

At present,the mechanical calculation of asphalt pavement structure has formed a relatively standard system and has been reflected in the specification.However,the existing mechanical calculations are usually calculations for certain fixed points selected based on experience.The mechanical response and stress state are still in a fuzzy state.In addition,there is a lack of systematic research on the influencing factors of asphalt pavement mechanics.Finally,the existing mechanical analysis is usually a qualitative analysis of the size of the mechanical parameters,and it is still unclear whether the structure is damaged and the location of the damage.Therefore,in response to the above problems,a complete set of programs such as a three-dimensional space full-volume calculation program,a three-dimensional stress state calculation program,and a damage analysis program based on strength theory have been written to express the mechanical response and space of the pavement structure under different service conditions.The stress state,the systematic study of the mechanical influence of various factors on the pavement structure,and the damage analysis combined with the strength theory,so as to give specific guidance and suggestions for the application of asphalt pavement engineering.First,according to the calculation results,the distribution law of tensile stress and shear stress in the asphalt pavement is summarized.The tensile stress appears when the modulus attenuates greatly from top to bottom,and the shear stress changes in the layer with relatively large modulus.Diffusion transfer from top to bottom.The difference between stress and strain distribution is analyzed,and it is believed that the reason is that the modulus has too much influence on strain.The spatial stress state distribution characteristics of various types of asphalt pavement structures are expressed through the three-dimensional full-volume analysis model.Analyzed the influence of load type coefficient,interlayer bonding state and Poisson’s ratio on the mechanical response and stress state of asphalt pavement.The analysis results show that the load action coefficient m affects the structural mechanical response and similar function distribution images;under sliding conditions There is a dangerous stress state with greater stress and greater stress level;the greater the Poisson’s ratio,the greater the compressive stress and the less the shear stress.Secondly,according to the relationship between the modulus and the temperature,the dynamic evolution analysis method of mechanical response and stress state based on temperature change is proposed.The changes in the mechanical response of the two structures of the strong base thin-surface asphalt pavement and the combined base asphalt pavement in one year are calculated.The calculation results show that the distribution and value of the mechanical response fluctuate continuously over time,and the mechanical response distribution has obvious seasonality.Spring and autumn can be regarded as the transitional stage of the two seasons of winter and summer.The summer structure is more inclined to pure compression without tensile stress,and the winter structure with low temperature is more inclined to tension and compression.According to the dynamic evolution analysis method,the influence difference of the influencing factors at different temperatures is further analyzed.Finally,the strength theory suitable for asphalt mixture is compiled into the program to calculate the safety factor,and the distribution of the safety factor and the most dangerous location of damage under different conditions are calculated in the form of map and three-dimensional volume.The distribution of safety factors of different structures is calculated,and the analysis results show that the most dangerous position is usually near the area below the inner edge of the surface load circle,the middle area of the two load circles of the second layer of the surface layer,or the position where large tensile stress occurs.The strength conversion coefficients suitable for asphalt pavement materials at different temperatures are proposed.Based on this,the dynamic evolution analysis method is used to calculate the change of asphalt pavement damage in a year and the most dangerous locations that are prone to damage in different seasons.In winter,the two-way tension-one compression zone and the one-way tension two-way compression zone of the surface layer are prone to tensile cracking,and the surface layer is unlikely to be damaged under pressure.The two-way compression zone below the edge of the load circle in summer may be crushed.This study systematically studied the problems related to the mechanical response and stress state of the asphalt pavement and compiled related calculation programs,which has a certain value for the structural design and engineering application of the asphalt pavement.