Influence Analysis of Thermal Stress of Flexible Function-Layer to the Cement Concrete Pavement Structure

The flexible function-layer is set between the cement concrete pavement slab and the semi-rigid base, which not only can lessen the influence of rain infiltration on subgrade and pavement structure but can also improve the contact condition of the slab and base so as to reduce the early cracking of cement concrete pavement slab caused by drying and temperature shrinkage. The 3-D finite element (FE) method was used to analyze the influence of the thermal stress of cement concrete pavement structure by the thickness and modulus changes of the function-layer. The results indicate that, first, under the positive and negative temperature gradient, the thermal stress of pavement structure was significantly influenced by the interlayer combination coefficient, whose increase would lead to a greater slab thermal stress. Second, the thermal stress of flexible function-layer and base decreased while the interlayer combination coefficient increased. The slab thermal stress linearly declined with the slab thickness, while the thermal stress of function-layer and base showed a nonlinear growth trend. The slab thermal stress was little affected by the thickness change of function-layer, but the higher modulus value of the function-layer, the greater thermal stress of pavement structure was observed. With the aforementioned analysis, this paper puts forward the reasonable function-layer thickness and modulus values.