Study On Optimum Design Of Squeezed Branch Pile

With the continuous development of the construction industry,the gradual rise of high-rise buildings,the increasingly complex geological conditions complexity,and the stringent requirements of the market economy,the pile foundation technology is facing an unprecedented new challenge.Faced with such a grim situation,in the 1990 s,expanded pile foundation technology appeared.Squeezed branch pile is increased the expansion of a process based on the traditional filling pile.With special equipment,some branches or bearing plate are set along the pile body of different depth.The force bearing properties of the supporting plate are utilized by the squeezed branch pile.The load can be transferred one by one,and unloaded one layer by one layer.The pile settlement and the load can be reduced greatly,and the pile has good stability and high bearing capacity.As a new type of pile foundation,squeezed branch pile is widely concerned by the scholars and the industry,for its reasonable stress pattern and superior economic benefit.But because of the existence of the supporting plate of the squeezed branch pile,the mechanical behavior of the pile is more complicated than other type.At present,the researches on the load transferring behavior of squeezed branch pile is not deep enough,the reasonable spacing of bearing disk and branch diameter is still not very clear,and there are lack of theoretical calculation and experimental research of scientific and rational.Therefore,based on the existing research results,in this paper,GTS Midas finite element analysis is taken as a means to optimize the design of the squeezed branch pile,and to promote the application and development of the squeezed branch pile in our country.The main research contents of this paper are as follows:(1)Two-dimensional finite element model of squeezed branch pile is established with the finite element software Midas GTS.The data integration of the compression of the soil around the pile under different vertical load is carried out.Then the load transfer characteristics are analyzed.The results show that the plate body from top to bottom in turn exerts force bearing performance.The load of the first supporting plate is the largest.The loads of the other supporting plates are decreased from top to bottom.Therefore,the soil properties of the first supporting plate have great influence on the whole pile bearing capacity;(2)25 group models of two dimensional with different plate spacing and branch diameter are set up by Midas GTS.Through the data integration of the distribution of the displacement field under different vertical loads,the corresponding Q-s curves and vertical single pile bearing capacity were obtained,and the orthogonal analysis was carried out.Influence of plate spacing and branch diameter on vertical single pile bearing capacity of squeezed branch pile can be obtained.The results show that: when the branch spacing D are the same,the bearing capacity of the pile increases and then decreases with branch diameter D increasing;when the branch diameter D are the same,the most bearing capacity of the pile increases and then decreases with the branch spacing D increasing;(3)According to the influence of the supporting plate spacing and the diameter of the supporting plate on the bearing capacity of the vertical single pile,two aspects design optimization method of the squeezed branch pile are summarized.The results show that,two times the diameter of the supporting plate is preferred to select for the diameter of the pile,which can make the diameter of the supporting plate is not too large or too small.It can avoid the bad results caused by the plate size;for branch spacing,branch spacing is preferred to select 2~3 times given plate thickness.It can reduce bad results caused by the too dense or too loose supporting disc.