Shandong Asphalt Pavement Division And Dynamic Response Analysis

Shandong province has the long history in highway construction, especially in theconstruction of expressway. In the long-term engineering practice, it has the characteristics ofthe pavement structure and material properties. But it is similar to other provinces, thedamage of pavement is also very prominent. Lots of practice have shown that pavementtemperature has significantly effect on its bearing capacity and performance, how to predictpavement temperature distribution accurately with weather conditions becomes a key factorsin optimizing asphalt pavement structure and material design. At the same time, in order tounderstand the mechanism of pavement failure comprehensively, the research on pavementmechanical behavior under complex conditions is crucial. Mechanical response analysis wasperformed under complex conditions, and it was help to study the degradation of pavementstructure and to provide the guide for select the reasonable pavement structure, and putforward technical measures for prevent the pavement from damage, this will be contribute tomake sound development for highway infrastructural construction.By means of the detection for the test road, asphalt pavement temperature distributionunder Shandong province was analyzed, due to the thickness of asphalt layer in expressway,temperature changes along the pavement depth, the near to the surface, the bigger pavementtemperature is, so the distribution of SMA and AC is more severe than LSPM layers. Hence,pavement surface temperature, air temperature and measuring time was selected to theparameters for pavement temperature prediction, and pavement temperature predictionmodels for upper asphalt layers(such as SMA or AC layer) and bottom asphalt layer(such asLSPM)were built separately. Owing to prediction model, it has provided convenient methodfor understanding pavement temperature distributions.Considering the influence of climate conditions such as temperature and raining,meteorological data in the past30years was analyzed, and combing pavement temperatureprediction model, the indexes used to climatic regionalization were determined, which are themaximum pavement temperature, extreme minimum pavement temperature and rainfall.Asphalt pavement high temperature was divided into5regions, the dividing line is56degrees,58degrees,60degrees and63degrees. The high-temperature distribution trend is higher inland than coastal areas, northwest than southeast. The second division into districts arerainfall, and it was divided into3regions by the dividing line of600mm and700mm.Characteristics of rainfall distribution increased gradually from northwest to southeast. Thereare great difference on pavement temperature and rainfall with different climaticregionalization. Great difference of annual range of temperature was appeared between thenorth regions and mid-regions; there are seldom rainfall and high temperature in south regionsof Shandong Province. Due to the influence of marine climate, Peninsula region has littledifference in temperature, rainfall and number of rainy days.FLAC program was adopted and analyzed for numerical simulation, dynamic responseof saturated asphalt pavement was analyzed as well as sensitivity to parameters. Dynamicload has great influence on vertical deformation, horizontal stress and shear stress of saturatedasphalt pavement. After load disappearing, pavement responses are still on, but pore waterpressure was dissipated rapidly, this is because excess pore water pressure was made by thechange in the mechanical boundary, when mechanical boundary healing, its pore waterpressure will be disappeared immediately, so dynamic load has little influence on pore waterpressure. With increasing the modulus of asphalt layers, the vertical deformation, verticalstress and shear stress are all reduced, instead horizontal stress increased. The depth of asphaltlayer has little influence on vertical deformation, vertical stress and shear stress than that ofmodulus. The increase in the thickness of asphalt layer， which can reduce the pore waterpressure below asphalt layers.Finally, On the basis of asphalt pavement structure of expressway in Shandong province,local temperature conditions and meteorological data were considered, asphalt pavementdynamic responses were counted under the field of temperature and stress with ABAQUSsoftware. Simulation calculation was taken and comparatively analyzed by differenttemperature parameters, the results showed that asphalt layer had the good properties fortemperature degrading, when coefficient of heat conductivity was raised, pavementtemperatures in different depths increased synchronously; the bigger specific heat capacitywas, the lower temperatures in different depths were. Pavement surface had the biggesttemperature stress variation in the whole pavement structure. The deeper pavement was, thesmaller stress variation was. Horizontal stress appeared tensile stress. Under the same wheel load, the higher the temperature was, the bigger stress gradient was. Shear stress mainlyappeared in the asphalt layer. With the temperature rising, shear stress spread into deeperdepth in the asphalt layer. So when the temperature was high, the pavement distress may bemainly shear stress. Vertical stress appeared compressive stress in the asphalt layer but tensilestress in the base course. The variation in temperature was not significantly affected verticalstress, from the above analysis, we can draw a conclusion that the effect of the coupling effectwas not negligible. When the field of temperature and stress coupling effect, the maximumtensile strain was located at the bottom of the subbase layer, and tensile stress change appearsgently at the bottom of base and subbase. The maximum compressive stress was located at thebottom of asphalt layer, and the maximum shear stress was located at the bottom of asphaltlayer, minimum shear stress was located at the bottom of subbase. The shear stress in theasphalt layer appears little waving and down trend. The maximum fluctuate appeared on thesurface but it was not dropped. The maximum vertical stress was located on the top ofpavement surface, and decreased progressively along the depth increased. Vertical stress inthe asphalt layer appeared waving and decreased progressively, the maximum value appearedon the top of surface. All of these findings will contribute to find the rule of structuredistortion, and it can control effectively and prevent pavement from damage.