Model Test And Theoretical Analysis Of The Engineering Properties Of The Composite Ground With Defective Pile Under The Condition With Lateral Pile

Composite foundation is a new way of the foundation treatment. It has been used in engineering practice generally for its economic feasibility and technical feasibility.The theory of composite foundation with defective piles is not such complete, some model test with defective piles and lateral piles has been carried out.The settlement and load transfer mechanism of the composite foundation has been analyed. The main works of this paper are presented as follows:1. The composite foundation, defective piles and interaction of piles and soils in the composite foundation have been summarized.2. Some concepts in the composite foundation especially its function and failure mode have been introduced. Advantages and disadvantages of some methods have been evaluated and some suggestions have been given based on recent research about the function of composite foundation and computing method of bearing capacity and deformation in composite foundation with vertical reinforcement.3. The testing goal and testing method have been fixed. Model test with defective piles has been carried out. Settlement and load transfer mechanism of composite foundation with defective piles has been observed using cyclic loading and unloading.The pierce deformation in lateral piles have been analyzed under cyclic loading and unloading in composite foundation with defective piles. The distribution rule of axial force and frictional resistance in lateral piles(long, normal, short) and normal piles and defective piles has been analyzed. Pile features of composite foundation with or without the lateral piles have been compared.4. Based on the contest result of model test, the character differences of the composite foundation with defective piles without lateral restraint under cyclic load have been analyzed. The result shows that the character of normal piles is better than defective piles, the lateral restraint offers more decrease of foundation settlement and limits the lateral deformation of composite foundation and improves its bearing capacity to prevent it from damaging.