Reliability Study Of Asphalt Mixture Based On Bending Stiffness Modulus Decay

Fatigue has always been the focus and difficulty in road engineering.Reliability,as the determination of health and service ability of materials and structures,has attracted more and more attention in design safety and quality control.Secondly,the function of reliability analysis based on bending strength modulus is constructed by using three-point bending fatigue test.The reliability of Monte Carlo direct simulation sampling method is realized by ab programming,and the law of reliability in the process of bending stiffness modulus changing with loading process is studied.Finally,through the finite element ABAQUS simulation analysis,the reliability of asphalt pavement structure in the service period with action times change law.Therefore,based on the laboratory test,the asphalt mixture based on modulus decay is studied in this paper.The law of reliability change.The contents of the study are as follows:(1)Three-point bending fatigue test.By studying the influence of the test parameters on the three-point bending fatigue test,the experimental loading temperature,stress ratio and loading speed are determined.Then,based on the three-point bending fatigue test,the bending fatigue life,initial bending stiffness modulus and bending stiffness modulus of asphalt mixture under the corresponding stress ratio are measured,the probability density distribution form of fatigue life is analyzed and finally determined as lognormal distribution form.(2)Study on decay Law of bending stiffness Modulus of Asphalt mixture According to the results of three-point bending experiment,the decay model of bending stiffness modulus is established.The model parameter m is obtained by comparing the test results of model fitting results.The quantitative relationship between model parameter m and stress ratio is analyzed.After dimensionless treatment,the relationship between bending stiffness modulus ratio and fatigue life ratio is analyzed.It is concluded that the bending stiffness modulus shows a three-stage decay law in the loading process: the first stage decreases rapidly,accounting for 10% to 20% of the whole loading cycle,the second stage approximately linearly decreases steadily,accounting for 60% to 70% of the loading cycle,and the third quarter stage accelerates to the failure stage,accounting for 10% to 20% of the whole loading cycle,which lays a foundation for the study of reliability development and change.(3)Study on reliability change law of asphalt mixture.Based on the decay law of bending stiffness modulus,the reliability analysis model of asphalt mixture is established,and the reliability analysis function based on fatigue life is established by taking bending fatigue life as random variable.The reliability under the corresponding stress ratio is calculated by Monte Carlo direct sampling method with the help of Matlab program.Finally,the variation of time-varying reliability of asphalt mixture with loading times is analyzed as three stagesand 100% stationary stage,rapid decline stage,0% stable stage,and the greater the stress ratio,the faster the reliability decline.The relationship between reliability and bending stiffness modulus during loading is verified and studied.the results show that the bending stiffness modulus decreases slowly at the beginning of the test,and it is found that the change of reliability and bending stiffness modulus is out of sync,and the reliability is still in the stage of rapid decline at the end of the test.Get different orders.The reliability of the flexural modulus provides theoretical basis for controlling safety stage and pavement design and maintenance.(4)Study on fatigue reliability of pavement structures based on finite element ABAQUS.Based on the ABAQUS finite element simulation,the mechanical response of pavement structure is analyzed,and the results of tensile stress distribution of pavement structure layer are obtained.Then the reliability analysis function of pavement structure with the maximum tensile stress at the bottom of the extracted structure layer as random variable is established.Based on the Monte Carlo method,the reliability of the pavement structure is decreased with the increase of the number of axle load and service life.The speed is accelerated and the number of axle loads is sensitive to the reliability analysis of pavement structure,which reflects that traffic flow should be reasonably controlled in road operation,and the corresponding monitoring means should be adopted to determine the safety state of pavement structure to make the pavement structure reach the longest service life.