| Cracking is one of the main diseases of asphalt concrete pavement,which will lead to other diseases of asphalt pavement more easily due to asphalt pavement will more vulnerable to precipitation and climate.Peridynamics is a theory that uses integral equations to describe the motion of issues,which can better solve the mechanical problems of discontinuities.So,Peridynamics has theoretical advantages in studying the cracking of issues,and is expected to become a new method to study the cracking of asphalt concrete.The peridynamics model of asphalt concrete was established in this study.The influence of input parameters of peridynamics model on low-temperature performance index was studied by combinating semi-circular bending test and numerical simulation.Then verify the effectiveness of the model and parameter selection was verified and the model was applied to study the influencing factors of low-temperature crack resistance of asphalt concrete.The main contents of this paper are as follows:Firstly,the semi-circular bending test of asphalt concrete based on the theory of fracture mechanics was using to obtain five crack resistance indexes: stress intensity factor,J-integral,fracture energy,flexibility index and crack resistance index.The characteristics of the five indexes were explored,and the evaluation effect of the five indexes on the crack resistance of asphalt concrete was studied by statistical method.The test results show that the flexibility index can reflect the influence of nominal maximum particle size and loading rate;The stress intensity factor and crack resistance index can reflect the influence of loading rate;The energy index fracture energy and Jintegral can not reflect the influence of other factors except for temperature;With the increase of temperature,the fracture energy and J-integral increase,and the J-integral can better distinguish asphalt concrete with different characteristics at-24℃;The sensitivity of stress intensity factor,flexibility index and crack resistance index to loading rate is higher than that of fracture energy and J-integral.The variability of flexibility index is higher than the other four indicators.Compared with flexibility index,crack resistance index can better distinguish asphalt concrete with different particle size composition.And then,the peridynamics numerical model of semi-circular bending test of asphalt concrete based on the theory of peridynamics was established.Asphalt concrete was divided into two systems: aggregate and asphalt mortar,and the corresponding constitutive relationship was established.The bond between the two systems was established by series model.The peridynamics parameters were selected as follows:the unit thickness and unit length of the specimen are both 0.5mm,the neighborhood radius is 3 times of the unit length,and the critical value of the local damage function is 0.45.The simulation results and test results were compared to each other and the simulated load displacement curve was basically consistent with the test results.The influence of material parameters on low temperature performance index was also studied.The results show that the low temperature crack resistance index is sensitive to aggregate stiffness and mortar stiffness,but not to aggregate fracture energy,aggregate compressive strength,mortar fracture energy and mortar compressive strength.The relative error between the simulated value of fracture energy and the experimental value is 4% ～ 11%,which proves the rationality and effectiveness of the numerical model of peridynamics and the selection of input parameters.Finally,the effects of precut joint length,void fraction and loading rate on the low temperature performance index of asphalt concrete were studied by using the numerical model of semicircular bending test.The results show that the fracture energy decreases with the increase of void fraction.With the increase of loading rate,the stress intensity factor increases,the crack resistance index decreases,the fracture energy decreases. |
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