Research On Fatigue Failure Mechanism Of Asphalt Mixture Based On Dissipated Energy

Fatigue failure of asphalt mixture is the main disease of asphalt pavement and one ofthe main issues to consider in asphalt pavement structure design. Deep study in failuremechanism of asphalt mixture certainly will promote the asphalt mixture’s fatigueperformance and road performance. The commonly used methods for the fatigueperformance study of asphalt mixture mainly have three kinds, which can be listed asfollows, phenomenon of mechanics method, damage mechanics method (includingmechanical approximation method, continuum damage mechanics method), energy method.Considering some restriction in mechanical approximation method and damage mechanicsmethod in traditional research process, as well as research facilities which caused byenergy method’s research ideas “concerning state, ignoring the process”, this paper willstart from the energy threshold in energy method and conduct the research to thedestructive mechanism of asphalt mixture fatigue.Based on the basic principle in energy method, this paper introduces the concept ofasphalt mixture fatigue damage threshold. Combining the four point bending fatigue test ofasphalt mixture with rectangular beam, the paper design the asphalt mixture of microwound healing test and verify the existence of asphalt mixture fatigue damage threshold.Paper also gets the key threshold value of asphalt mixture fatigue damage through bendingtest. Then the paper simulate the viscoelastic model of asphalt mixture through the creeptest data for modified asphalt mixture, and validate rationality of the fatigue damagethreshold calculated by viscoelastic model parameters. The purpose is to tell other how toevaluate fatigue performance of asphalt mixture through the asphalt mixture fatiguedamage threshold.Finally, based on dissipated energy in four point bending test of the asphalt mixturespecimen, and related prediction model of asphalt mixture, fatigue failure criterion has been discussed and argued extensionally. This paper put forward the fatigue failurecriterion according to the sudden change of relative change rate of dissipatedenergy(RCRDE). In this paper, considering the experimental conditions and resources atthat time, the main work to do can be listed as follows:1) In order to discuss energy loss of asphalt mixture under cyclic load from the angleof energy threshold, this paper introduces energy threshold and discusses the fatiguedamage threshold and the evaluation method of asphalt mixture in detail.2) According to the experimental conditions and resources, and comparison of thevarious methods, all kinds of test methods, test piece form, this paper determines the testspecimen type, and designs a test scheme which matches the subject.3) Combined with previous studies, and based on four points bending fatigue test andbending test, the paper design the asphalt mixture micro wound healing test and prove theexistence of asphalt mixture fatigue damage threshold and rationality.4) By the statistical theory of fracture shows, we need a damage threshold in theanalysis of the loss of material failure behavior. Based on the asphalt mixture fatiguedamage threshold and combined with the four points bending fatigue test, bending test andcorrelated test specification, the asphalt mixture fatigue damage threshold value can becalculated.5) Based on the creep test of modified asphalt mixture, this paper fits the viscoelasticmodel parameter of modified asphalt mixture and obtains fatigue damage threshold’srational validation through asphalt mixture model parameters.6) Based on the dissipated energy of relative change rate(RCRDE), and four pointbending fatigue test and data analysis, this paper put forwards the change of RCRDE as thecore of fatigue failure criterion.7) Combined with the fatigue performance prediction model launched by fieldscholars, the steady process value (SPV) in RCRDE can be used to fit the model, andconfirm that the dissipated energy of relative change rate (RCRDE)’s sudden change as thefatigue criterion is rational. The research verify from the side way that energy thresholdcan be used as the evaluation of the asphalt mixture fatigue performance.