Study On Expansion Mechanism Of Reflected Cracks On Low Temperature Asphalt Pavement Based On RFPA

The problem of asphalt pavement structure damage caused by the reflecting crack of asphalt concrete pavement is an urgent problem in many areas of our country.Especially in China's high-cold areas,the cost of road works is high,repair work will be more difficult.Therefore,it is necessary to study how to reduce the probability of the formation of reflective cracks and reduce the degree of damage to asphalt pavement structure is very necessary.However,due to the particularity of the pavement structure,the use of outdoor test methods will bring a lot of inconvenience,it is difficult to assess the level of damage to the overall structure.Through the literature summary,it is found that the test is lacking in measured data and the effect of the crack structure on the expansion of reflected cracks,so based on engineering examples,this paper uses the method of RFPA(Realistic Fail Process Analysis)numerical simulation to reduce the cooling rate,crack spacing,The inclination of the crack explores the formation and expansion of reflective cracks.The results of the study are as follows:(1)Using RFPA-THERMAL version,taking into account the non-uniformity of the material of asphalt pavement structure,a typical double-layer structure model was established using the structural parameters that have been in practice with the project.The formation and expansion of reflected cracks at different cooling rates were observed.The relevant conclusions are as follows: With the increase of cooling rate,the more rupture dyspart of the asphalt surface structure,the greater the degree of damage,the reason is that the temperature stress produced by the larger cooling rate will be greater than the heat transfer capacity of the road structure,resulting in a large number of temperature stress can not be transmitted to the grass roots in time.Therefore,in the actual engineering should try to choose the heat conduction capacity of better materials,or slow down the impact of temperature on the road structure.(2)The effect of the reflection crack spacing on the expansion mechanism of the reflected was studied by the cracks that were pre-fabricated in the grass roots.The results show that a larger stress le crack vel will be shown in the larger gap,but most of the stress in the large spacing model will cause the crack to expand into thegrass-roots structure,and only a small part of the stress will be used to form a reflective crack.Therefore,in the actual engineering,it is suggested to optimize the selection of grass-roots structural materials,and it is necessary to increase the anti-cracking properties of grass-roots materials.(3)Considering that fracture distribution will affect the stability of the whole structure pre-fabricated five models with different inclinations.Under the low temperature,it can be found that with the increase of the inclination of the prefabricated crack,there will be some difference in the extension path of the reflected crack.The tilt angle of the reflected crack is proportional to the inclination of the prefabricated crack.In addition,with the increase of the inclination of the preset cracks,the degree of damage at the surface of the surface will decrease,while the degree of damage at the middle position of the surface structure will increase significantly.The final test also shows that the pre-fabricated large angle cracks in the grass-roots structure can delay the occurrence of reflective cracks to a certain extent.This provides a new way of thinking for the prevention and control of asphalt pavement in practice.