Research On Preventive Technology Of Semi-Rigid Asphalt Pavement Reflection Crack

In our country, to get stronger base and reduce the thickness of HMA layers, semi-rigid base is widely used in highways. Reflection cracks are common diseases of semi-rigid base asphalt pavements; they not only affect road appearance and riding comfort, but also shorten pavement service life excessively. Traffic load and temperature load are two main factors accounting for its formation and propagation. This paper bases on Luohe to Zhumadian highway pavement disease treatment project the Beijing-Zhuhai national trunk highway. In this Paper, linear fracture mechanics and finite element method are employed to give a full analysis to the mechanism of reflective crack's propagation and the effectiveness of intelligent materials alloy sandwich control surface reflection is studied as well.Firstly, after depicting the singularity of stress field at the top of crack, the finite element method to calculate stress intensity factor of plain fracture problems is founded. Then it introduces the ANSYS finite element analysis software, and pointed out that it is applicable and efficient to be used to calculate the crack tip stress intensity factor.Secondly, the structural response of pavement surfing reflective cracking is deeply analyzed in terms of traffic load and thermal load. As for traffic load, two situations were analyzed, symmetrical load and asymmetric load, in each of them, crack tip stress intensity factor were calculated, and also the effect of structural parameters were analyzed. Pavement's temperature distribution field when suffering sudden temperature dropping was numerical simulated. Crack tip stress intensity factor caused by thermal stress were computed, structural parameters'sensitivity analysis were made as well. Then, reflective crack's propagation model under traffic load coupled with temperature load was analyzed.Thirdly, the intelligent materials alloy SMA and ISCA thin stress absorbing layer are introduced. According to the actual pavement structure of the Luohe to Zhumadian highway, the calculation model is set up. And the finite element software ANSYS is used to calculate the crack tip stress intensity factor of the pavement structure in terms of traffic load and thermal load. The results of the analysis showed that the ISCA composite sandwich had a better dissipation of crack tip stress intensity factor, and can inhibit or retard reflective cracking expand to the surface. During the discussion of the stress dispersing effect that the ISCA composite sandwich specific location, while the parameters of the sandwich change impact analysis is also carried out. At last, a set for the actual operation of the reflective crack control programs is proposed.Finally, combined with field testing and follow-up observation that the theoretical analysis results are verified, and the ISCA composite sandwich controlling the reflective crack is feasible and efficient. Through the above-mentioned work, the relevant reference for the follow-up study is provided.