Experimental Investigation Of The Rigid Long-short-pile Composite Foundation About The Interaction Mechanism Between Long-pile And Short-pile

The study of composite foundation is active in geotechnical engineering in China in recent years, and the rigid long-short-piles composite foundation is widely used in the class of composite foundation. As the application in the high-rise building foundation treatment the settlement and bearing capacity of long-short composite foundation are carried out extensive research, but for the mechanism study of long-short composite foundation is still in its infancy. This thesis based on reduced scale model test about rigid long-short-piles composite foundation, and the interaction between long-pile with short-pile has been studied.Firstly, through the static load of five groups which include two groups of single pile, two groups of composite single pile, one group of composite four piles.Load-settlement curve, pile axial force curve, pile-side friction has been respectively carried on the comparison and analysis. Finally, using ABAQUS finite element software, modeling the model test by 1:1, analyzes the distribution about the axial stress of pile and pile side friction, and compared with experimental data. Draw the following conclusions:(1)For short pile which in three different forms of work, their pile axial force distribution law is inconsistent. The single pile showed a trend of decrease gradually; the composite single pile showed a trend of increases at first then decreases; the composite four piles showed a trend of that as the same with he composite single pile.(2)For long pile which in three different forms of work, their pile axial force distribution law is inconsistent. The single pile showed a trend of decrease gradually; the composite single pile showed a trend of increases at first then decreases; the composite four piles showed a trend of that as the same with he composite single pile.(3) For short pile which in three different forms of work, their pile side friction distribution law is inconsistent. The composite single pile exists negative friction area where near the pile top location; the composite four piles showed a trend of that as the same with he composite single pile.(4) For long pile which in three different forms of work, their pile side friction distribution law is inconsistent. The composite single pile exists negative friction area where near the pile top location; the composite four piles exists two areas of negative friction, the first area located in the same location of composite single pile, the second area located in the scope of short pile end. Think that because of the develop of short pile end, the soil near short pile end moved down, then the soil near long-pile moved down too, and the long-pile side friction was changed.