Numerical Analysis of Stress Intensity Factors in Airport Asphalt Pavement by Aircraft Wheel Loading

Ground facilities are an integral part of the airport, which the most important of them is runway pavements. One of the difficulties and the inevitable failure of the pavement are cracking. Cracking in flexible pavements is a distress seen in the most flight zones. Therefore, it is important to take action to reduce the speed of its spread. In this study, field data of Kerman airport (Iran) were used to achieve the mentioned goal and to adapt the results to the reality. Also, the real values of the thickness and density of the layers and other layer properties obtained from the experiments were used. By using finite element software for runway pavement, a crack was modeled and then its output was used to analyze the pavement in different modes. At first, by loads displacement to the position of the cracking, the place where loading causes the highest stress to the cracking was determined. Next, the different analysis in the targeted area was conducted to investigate the effect of the asphalt thickness changes, crack length changes and the temperature changes in the cracking behavior. The results of change in the crack length showed the stress intensity factor KI increase to 17% with increasing the crack length two times. The amount of stress intensity factor decreases with increasing the asphalt thickness. In other words, the crack growth rates decrease with increasing the asphalt thickness. The results showed that for each degree increase in temperature, the stress reduces by 3%, which reflects the importance of temperature parameter. It is recommended at the temperatures close to zero degrees or below zero, the number of flights to be limited.