| The asphalt pavement based on semi-rigid type base has got extensive application in our country's road construction because of its advantages, such as high intensity, low cost, good performance of globality and water stability. But semi-rigid type base course easy to produce contract crack and low- temperature shrink crack during running by the periodically change of temperature and repeated traffic loads, and this crack is easy to extend to the surface, it's so called reflection crack. The reflection crack not only affect the road appearance and drive comfort, and the most important thing is that greatly shortens the service life of road surface.Many researches has launched about the theory of road crack and the material and method of anti-crack both at home and abroad. Because the fracture mechanic can well reflect the existing crack in the pavement, so it has got better application in the analysis of reflection crack of pavement. Present research adopting fracture mechanic mainly concentrated on the stress state and the stress intensity factor on crack tip, through compare with tress or stress intensity factor to evaluate the ante-crack effect by different anti-crack materials or methods, less study has been done about fatigue life and the relationship about fatigue life and road structure parameter. This paper adopting fracture mechanics finite element model, and the theory of fatigue fracture mechanics, expatiates the theory and computational method of reflection crack's fatigue life under temperature loads. At the same time calculates and analyzes the influence factors of reflection crack's fatigue life to offer the theoretical foundation for anti-crack material and structure.Many materials has been adopted to reduce reflection crack, such as geotechnological grids or nets, present researches are mainly concentrated on the flexible interlayer, the concrete method is to set up a inter-layer of low elastic modulus and good toughness between pavement and semi-rigid base course, in order to absorb the crack tip stress, the method has wildly used in project practice at present, such as rubber asphalt concrete and STRATA stress absorbed system exploited by KOCH company.This paper research on the mechanism of the reflection crack on the basis of former study, and prepare new type of stress-absorbed material. This paper mainly include two aspect:1) This paper studies the reflection crack's expansion law and computing method of fatigue life when temperature changes. The influence of structure parameter and different anti-crack material and method on fatigue life has been analysis and the theoretical foundation for anti-crack material and structure can beachieved from the study.2) The anti-crack effect has been quantitatively calculated, and the influence of different elastic modulus of interlayer on anti-crack effect has been studied. At the same time study and prepare new type of stress-absorbed material and research its road performance. |
