Research On Law Of Crack Propagation Of Different Asphalt Pavement Structures Under Vehicle Load

Crack is one of the common diseases in the application of asphalt pavement, especiallyfor the semi-rigid base asphalt pavement, reflection crack is a particularly tricky question, andthe premature failure of asphalt pavement also comes from it. According to this problem thereare many preventive measures, and reasonable structure design is a good foundation to ensurethat the asphalt pavement performance is good. In recent years, the research on combinationof pavement structure becomes hot, and the pavement structure with graded gravel layerarouses road workers attention and is active in the fields of highway design and constructionbecause of its special performance, such as dissipating reflection crack, good drainageperformance, and excellent economy. In view of this, the paper does research on the law ofcrack extension of flexible base asphalt pavement and inversion structure asphalt pavementboth with graded gravel, and compare to typical semi-rigid asphalt pavement structure, then inturn calculates and compares the fatigue lives of different asphalt pavements which have veryimportant theoretical significance and practical application value.Firstly, investigate and then summarize stations of asphalt pavement cracks, includingappearance shape and the developing and even adverse effects of cracks, understand kinds ofdesign methods of crack resistance，and master major type and developing rules of asphaltpavement cracks. Secondly，study the extending rule of cracks in different asphalt pavementstructures, build plan strain model of the 4 kinds asphalt pavement with cracks respectively,computationally analyze the change of stress intensity factor on the top of cracks with thechange of extending depth of cracks based on fracture mechanics theory. Compare andanalyze crack propagation rule of different kinds of asphalt pavement and it is benefit fordesign and choose that which type of pavement to use. Do sensitivity analysis to stressintensity factor through taking change of the thickness and modulus of studied layer, and itcan provide a theoretical foundation for reasonable settings of material parameter for asphaltpavement. Finally, studies crack fatigue characteristics of different asphalt pavementstructures. Aiming at different pavement structures, respectively sets up plane strain and 3dfinite element model of intact pavement, and calculates load equivalent coefficients of thesesstructures and that with different material parameters based on flexural stress equivalentprinciple. Combined with calculated stress intensity factors, calculates and compares fatiguepropagation lives of load type cracks in different type asphalt pavement structures using P-Mstandards and Paris empirical formula, and studies the influence of material parameters onfatigue propagation life.