Study On The Numerical Models Of Asphalt Pavement Temperature Field

Research on the numerical model of temperature field under the extreme temperature, and predicting the worst temperature condition at any depth of the pavement structure can provide some theoretical guidance for asphalt pavement design. Based on the temperatures database tested for 2 years within the full thickness of the asphalt pavement, the variation of temperature for high temperature stage, low temperature stage and room temperature stage was analyzed. Applying the “double samples-plane” heat conduction device, the thermal conductivity for common semi-rigid base asphalt pavement materials was tested. The numerical model of extreme high temperature field and extreme low temperature field were identified through numerical regression analysis. The thermal conduction mechanism of asphalt pavement was analyzed. Temperature field for extreme high temperature moment and extreme low temperature moment were simplified to steady-state temperature field, and a polyline type of numerical model for temperature field was built. Comparative analysis were made for both the numerical regression mode and the poly temperature field.It can be concluded that asphalt pavement temperature changes periodically, especially for the daily change. And the temperature change was mainly in the asphalt layer and small in the base, basically unchanged in the sub-base. Thermal conductivity for cement treated gravel base and asphalt pavement respectively is approximately within 1.03~1.60W·(m·K)-1 and 0.70~2.10W·(m·K)-1. Key internal factor affecting the thermal conductivity of pavement material firstly is void ratio, secondly is particle size of aggregate, and external factor is temperature. Typically, the heat conduction of asphalt pavement is transient but not steady, theoretically, high temperature field and low temperature field has the same distribution law, except for the numerical difference and the opposite and symmetrical curve distribution. And the high temperature field tends to be transient, while the low temperature fields tend to be steady. The extreme high temperature can be described by the exponential decay numerical model, the temperature attenuate much in asphalt layer and tend to be stable in the base. The growing process of pavement temperature has described the changing of transient heat conduction to be a steady one. Consider from the heat conduction theory, temperature field close to steady state can be described by polyline type numerical mode. And the slope of polyline relates to thermal conductivity of each pavement layer. In Contrary, extreme low temperature has the same numerical mode with the high temperature field, but in the opposite direction, into increased. For the low temperature period, the temperature changing width of pavement is small, thermal conductivity of material is small, heat conduction property for pavement is weak and tend to be steady, and the corresponding numerical model can be simplified as line.