Pile-soil Interaction Study On Hammer-hit Pipe Pile

Hammer-hit pipe piles are widely used in bridges,buildings and other large-scale engineering foundations.However,the severe penetration process of hammer-hit pipe piles will cause serious squeezing effect on the surrounding soil,thus affecting the surrounding environment and buildings.The process of hammering the pipe pile into the soil is a very complicated dynamic process.It involves large geometric deformation,large displacement,nonlinear material,nonlinear contact between pile and soil,etc.So the study of the pile-soil interaction in the process of hammering pipe piles into the soil is also very complicated,but it has great application value.Therefore,on the basis of the predecessors,this paper conducts related research on the interaction between piles and soil of hammer-hit pipe pile.The main contents and conclusions of this paper are as follows:(1)By consulting a large number of relevant literature and summarizing the research status of pile-soil interaction,the finite element model and model test related scheme of Pile-soil interaction study on hammer-hit pipe pile are put forward,and the research content of this paper is formulated.(2)The finite element theory is used to analyze in detail the energy exchange during the contact impact between the pile hammer and the pile,and the relative sliding and squeezing process between the hammer pile and the surrounding soil occurred.a simplified model of continuous penetration of axisymmetric hammer-hit pipe pile is constructed.Displacement penetration method was used to achieve continuous penetration of piles by equivalent hammer hammering.(3)Through the finite element model analysis of the continuous penetration of the hammer-hit pipe pile,it is known that the soil element around the model pile is in the range of 1~2R times the diameter of the pile,and the soil element is squeezed and deformed by the continuous pile,and the big deformation and large displacement occur.In the stress zone of the pile,a large bottle-shaped small mouth is formed at the upper mouth,and a stress bubble is formed at the end of the pile.In the process of penetration of hammer-hit pipe pile,the impact of soil on the soil nearer to the pile is greater.As the distance increases,the radial displacement of the soil becomes smaller and smaller,and the compressive deformation of the soil is less than 3 times,and the radial influence range is approximately 9R.With the increase of the distance from the diameter of the pile,the uplift is smaller,and the surface uplift of the soil is the largest in the 3R range.The total resistance of pile penetration increases with the penetration depth,which shows the regularity of linear growth.(4)Through the continuous penetration model test of the indoor hammer-hit pipe pile,it is proved that the stress-strain,displacement and surface uplift of the soil are increasing with the distance from the diameter of the pile,which shows the decreasing trend.In the 3R range,the effect of piles on the surrounding soil is the most intense.Outside the 9R range,the effect of the pile on the surrounding soil is very weak.And the total penetration resistance of piles shows a linear growth trend with the depth of penetration.(5)Comparing the results of stress,strain,displacement and pile resistance test results of the continuous penetration of piles on the surrounding soil in the indoor model test,the differences between the experimental data and the numerical simulation results are calculated.the curve law accords with the numerical simulation results,and verifies the rationality of the simplified continuous penetration model of the hammer-hit pipe pile in this paper,This paper provides a good research method for studying the complex nonlinear dynamic characteristics of the pile-soil interaction of hammer-hit pipe pile.