Research On Behaviors Of Rigid Pile Composite Foundation In Soft Clay

In recent years, rigid pile composite foundation has been used in many engineering projects which show many great economic and social benefits, but the research on such composite foundation and the knowledge on its behaviors are still inadequate. This paper is intended to study the behaviors of rigid pile composite foundation and to develop methods for its bearing capacity and settlement calculation by experimental, theoretical and numeric means. The following are the main contributions.The first, some experiments have been conducted, including 6 group single concrete piles and 4 group 3-pile composite foundations' plate loading tests and 2 group 3-pile composite foundations' stress tests. The deformation and distribution of stress in the composite foundation was measured. According to these measurements, it is received that the piles shared in mostly load and the soils reach state of limit bearing capacity earlier. Besides, the bearing capacity calculation adapt to soft clay is gained. At the same time, the settlement calculations are analyzed and the advice is put forward it necessary to modify the modulus of composite foundation of soft clay layer.The second, based on the bilinear non-linear elastic model for soil and the analysis of interaction of pile-soil-cushion, the analytical solutions of load distribution and settlement of foundation can be gained. Then, the stress ratio and the settlement of foundation can be thereby obtained. It is proved credible with contrasted to experimentation's results. At the same time, the factors that influence the stress ratio arediscussed too. At last, some conclusions with practical and academic value can be obtained.Finally, behaviors of the rigid pile composite foundation are investigated by three-dimensional finite element method with the computer program ABAQUS. Factors influencing behaviors of the composite foundation under vertical load are studied. The influence factors were considered, such as cushion thickness and modulus, pile length, soil modulus, etc. Based on these analyses, methods of settlement evaluation are proposed.