Void Status, Based On Rigid Pavement Falling Weight Deflectometer (fwd) Assessment

Void beneath slab is one of the common damages of the cement concrete pavement, which influences seriously the service ability and the tired life-span of the cement concrete pavement. At present, the exact evaluation methods of void are acoustic attack,coring,deflection testing and so on. FWD get a broad application because of its merits such as simple practicality,field,celerity,nondestructive and so on. But the application of the FWD in the void is only based on the deflection to estimate the void. At present, the research hotspot is how to estimate void in ration with the deflection. The method based on the positive develop model of the deflection to interchange rigid pavement void is very effective. The method is in the explore moment because it runs short of logical positive develop model and theory. The application of the following weight deflectometer in rigid pavement void identification is researched in this paper. The main contents and significance of the paper are as follows:1. In this paper, the stress,strain and deflection of cement concrete pavement under void condition is mechanically analyzed, and the formulas of the stress,strain and deflection of the PCC pavement slab are deduced when void types are rectangle and triangle.2. Based on the elastic foundation slab, the displacement calculation models of the slab are established for winkler foundation in this paper. Assumed the size and the position of the void, the deflection with the load is solved. The displacement curves are simulated in void state. Using the fortran language the program for solving the deflection with finite method is developed3. In this paper, contrasting the displacement curves in serviceable condition and void state, a sort of simple and applied method which is comparison analysis method is built. This method is based on the theory that the deflection of the cement concrete pavement under uniform support at the action of the load is decrescent with the distance from the load point augment. By engineering proving, the method is a brief and effective method for the evaluation of the void. In this paper, the research results don't only offer a new thought and theoretic support for more research on void state, but also offer a technology support for making scientific injected scheme and logical maintenance measure. And the research results have important engineering value.