Response Analysis Of Cement Concrete Pavement With Cavity Beneath Slabs Under Dynamic Load

Now with the rapid development of economy and the progress of science and technology,the highway transportation industry has obtained large-scale development.But it was accompanied by the serious phenomenon of the road overload,which leads to the early damage of the cement concrete pavement in the initial stage of use.Among these diseases, the existence of void is very harmful to the stress of the cement concrete pavement,it affects seriously the character of service and the fatigue life of the pavement.For the cement concrete pavement,void beneath slab is relatively common.Therefore,this paper mainly studies damage effects on the pavement caused by void beneath slab.Due to the irregular pavement,vehicles on the road will have vibration on the road,and the influence of load on road surface and roadbed has relation to the load time and the road surface features.It is a typical dynamic load.Aiming at this problem, a typical cement concrete pavement structure model is selected in this article.By using finite element method, combined with the finite element program ANSYS, mechanical response of cement concrete pavement with void beneath slab under load is analyzed in the paper. We can get the distribution of tensile stress and vertical displacement of cement concrete pavement structure under different loads. The influence to the pavement of load, speed, void size and other factors can also be received.The main work is done as follows:⑴The void shape beneath slab is regarded as a square. And a three-dimensional model of cement concrete pavement structure is built to come forward the maximum tensile stress under the plate and the maximum vertical displacement on the layer by finite element calculation software.⑵The movement of the load on a flat surface is reduced to moving constant load and applied to the three-dimensional model of cement concrete pavement. By means of transient response analysis by finite element software, we can get the value of deflections and stresses of the road panel.⑶the load on uneven pavement is reduced to moving sinusoidal load and applied to the model of cement concrete pavement.By means of transient response analysis by finite element software ANSYS, we can get the status of deformation and stresses of the road.⑷The law of dynamic response to the pavement structure under different working conditions such as driving speed, vehicle load, void size is analyzed, and the results under three kinds of load is compared. It can be concluded that the moving loads on the uneven pavement lead to the largest deflection on surface layer and tensile stress under the plate.In other words, the vibration on the uneven pavement is most harmful to the road with void beneath slab.Several conclusions in this paper obtained through all the analyzes above has certain value to the structure design and construction management work of cement concrete pavement.Among them, while moving constant loads and moving sinusoidal loads applying on the concrete pavement, consideration to the impact of heavy traffic is the innovation of this paper.