Experimental Research On Carrying Mechanism Of Pile And Influence On Carrying Capacity From Distance Of Two Branches

The pile with branches and plates is the recent development of a new type of pile. Compared with piles with the same diameter, it has more carrying capacity and less deformation and displacement. If promoted in every field of civil engineering, it will receive great economic and social benefit. Based on the exiting research results of pile with branches and plates, the paper studied carrying capacity of pile under pullout loads, load transferring mechanism, stress distribution of piles and soil around piles, through indoor model tests and finite element simulation method. And it mainly studied the influences on carrying capacity and deformation of pile with branches and plates from different distances of plates.Firstly, through the data measured from indoor model tests, I drew Q-S curve and relation curve of pile axial force, from which we can find that pile with branches and plates has good load-bearing characteristics. When the load is comparatively smaller in the initial stages, axial force in the place where the plates are set did not change significantly, axial force of the pile is basically decreased linearly, showing that the carrying capacity of the pile is provided mainly by the lateral friction of piles. As the load increases, in the places where the piles are set, pile axial force changes significantly, which means that the plates come into play, increasing its share of the load, which supports the reason that pile with branches and plates has stronger carrying capacity than the standard diameter pile. At the same time, due to the impact of branches, the role played by lateral friction within a certain range of the branch will be affected, even negative friction can exist.Secondly, according to different piles, we did uplift resistance and compression experimental search, and drew Q-S curve and relation curve of pile axial force, measured the stress of soil around the pile, compared influence on pile's carrying capacity and displacement from different distances of plates. Test results show that, in uplift test under different distances of two piles, the carrying capacity reaches its highest under twice the distance of two plates, and reaches its lowest under three times the distance, capacity under one time the distance followed. This shows that it is not correct that the larger the distance between two plates is, the higher the capacity is. The Uplift capacity of piles is related with the distance between the plate and the top surface of the soil, the nature of the soil, anti-pull failure mode and so on. While the compression test showed that the carrying capacity of piles increase as the distance of plates increase, mainly because when the distance of plates increase, the carrying capacity of soil among plates increase.Third, through finite element simulation, I compared pile with plates and branches to straight pile as well as pile stress, stress of soil around the pile and displacement changes under different distance and so on.Finally, based on the reach work of this paper, I drew some meaningful conclusions, made a number of recommendations and prospect for future work.