Mechanism Of Pile-soil Inte Raction And Stability Analysis In Foundation Pit

In the 21 st century,with the rapid development of high-rises and super high-rise buildings,The foundation of the buildings is deeper and deeper.The design requirements of excavation engineering are also increasing.At the same time,the construction is more and more difficulty.In the type of deep foundation pit support structure,the row pile supporting structure is widely used because of its convenient construction,good lateral resistance and low cost;The research emphasis of support structure,mainly focused on the design and optimization of pile or the supporting structure instability in the overall control,or control of pile anchorage depth and bottom uplift,the occurrence of piping.Because the pile spacing is unreasonable,soil between piles is extrude.The research of this kind of situation is relatively few.This paper will use the finite element software to study this kind of situation.Because the local damage can not be reduced to two-dimensional problems,this article will be based on t he two-dimensional strip method to establish a three-dimensional strip column method.Hope to enrich the design and calculation theory of row piles.With the aid of the finite element software,the multiple sets of models are established,and by changing pile spacing,properties of soil and the excavation depth of load,to investigate the influence of these factors on pile soil slip geometry change.Then,the local stability of the soil is determined by the three dimensional strip method and the the limit excavation depth is calculated.The main research contents and conclusions are as follows:(1)With the pile spacing,the excavation depth increases or soil friction angle and cohesion strength decreases,the soil between the piles occur slip failure,geometry of sliding surface is a spherical surface.Only size with several of the above factors occurred some changes.(2)Based on the principle of the two dimensional Sweden slice method and the infinite strip method,the calculating formula of the stability safety factor of the soil between the piles is derived.(3)By programming the Excel software,the safety factor of the local stability of the soil between piles is calculated,which is consistent with the safety factor obtained by the finite element numerical simulation of ABAQUS.This verifies the rationality of the formula.