چكيده به لاتين
So far, different studies have been conducted to improve the quality of different characteristics of pavements. Various methods such as laboratory tests, field studies, as well as mathematical and finite element analysis have been used to achieve this goal.
A very important point that has been less addressed is the periodic temperature changes in the environment. Previous studies on the effects of temperature on asphalt mixes examines and compares sample behavior at a constant temperature. The topic of this research is the effect of temperature changes with time and the repetitive cycle of increasing and decreasing temperature on the asphalt mixture. The main purpose of this study is to investigate flexible pavement responses to temperature loading cycles with special attention to fatigue as one of the main causes of pavement failure.
For this purpose, the four point flexural beam fatigue test is first modeled using fixed strain method, in 3D in Abacus software. The results indicate that the asphalt mixture responses are more dependent on higher temperatures in the range of temperature changes applied to the asphalt mixture. In general, it can be said that in the conditions considered for this model, the fatigue life of the mixture may increase due to the reduction of the tensile stresses created beneath the asphalt beam.
In the next step, the dynamic characteristics of the model of a laboratory mixture are determined as the input data of the model, and samples of this mixture are tested for fatigue. The new model is made with the specifications of this asphalt mixture and its fatigue results have been evaluated with the test results. This comparison partially confirms the similarity of the results of the two simulation and experimental methods.
In the last step, pavement responses were investigated with a complete simulation of a pavement under the influence of a wheel load and temperature changes. In this case, due to the constant amount of traffic loading, under the alternating temperature cycle, more strains in asphalt pavement have been created than the constant temperature loading. Although strain changes in a pavement can be estimated by mathematical functions at a constant temperature, this is not possible due to intermittent temperature changes that lead to sudden changes in strain rate changes
