The Analysis And Evaluation Of Void Beneath Slab In CCP

Void beneath slab is one of the common structural damages of the cement concrete pavement. The appearance of void is very unfavorable to the stress of the cement concrete pavement, it influence seriously the service ability and the tired life-span of the cement concrete pavement. That local void beneath concrete slab on service exists objectively. The evaluation of void is very difficult because it can't detect from the surface of pavement. At present, it hasn't effective method. The paper has done some research work about the void beneath slab. The main contents of the paper are as follows: 1.The paper introduced briefly the development of the cement concrete pavement. And besides, it gave a simple review of the mechanism and the model of void, the method of mechanics account, the method of evaluating void. 2.To avoid and reduce the void beneath slab, the paper analyzed the fact of void beneath slab from three respects, which include the structural design, construction quality and maintenance and management. And it gave the mechanics model of the slab. 3.This paper used the three-dimension finite element method to analyze the connection of void, load transfer capacity and deflection, which offered theoretical basis reference to effectively evaluate the void beneath slab. 4. The paper used the FWD as the tool to evaluate the void beneath slab, and introduced the first critical load-transfer condition to eliminate the influence of the deflection which caused by joint load transfer capacity and void beneath slab. Then it provided evaluation index. At last, this paper proposed the method of evaluating void and drew the picture of the void area which appeared beside the transverse joint. 5. Based on the actual project, it discussed the technology of mud jacking for the old cement concrete pavement.