Experimental Research On Rigid Pavements

The work presented in this thesis is part of the research project-Similitude Laws and Nondestructive Diagnosis on Concrete Pavements, which is supported by China National Science Foundation. 9 slabs were tested to failure with factors of slab thickness, size ratio of geometrically similar slabs and loading place taken into account. The main contents include:1. The mechanics performances of geometrically similar slabs under static load on the same elastic foundation are similar, according to the analysis of slabs with similitude laws and tests of soil stress under rigid pavements with different size ratios.2. The scaling law is a power law if, and only if, a characteristic dimension is absent. The experiments result proved the correctness of Westergaard equations when the load was applied to the middle or the edge of slabs. The situation, which the load was applied to the corner of slabs, was different from what Westergaard equation described.3. Based on the analysis of the mechanic characteristics of the earth, a concept, the magnifying effect of the subbase, was proposed to eliminate the disunity in calculations. Many facts in concrete pavements can be explained by using this concept. A numeric example using the finite element method was given to show the correctness and effect of the concept.4. A fitted equation was given to ultimate load of geometrically similar slabs with size effects taken into account. The equation approached what deduced by Z. P. Bazant with mechanics of failure. A quasi-elastic method was proposed to decide the maximum load of rigid pavements under static load on the basis of experiments of reduced scale slabs, which was the key point for the similitude law to be used practically.5. It was found that the load location changed with the thickness of slabs increasing through the analysis of the relationship between ultimate load and slab thickness. It was never found by any elastic analysis before. The ultimate load was controlled by the load on the middle of slabs when the slab thickness was more thanapproximately 43 cm.6. The similitude law was deduced by analysis of the differential equation of slabs on elastic foundation. The law was proved by the dynamic tests.