Study On Vertical And Horizontal Coupling Vibration Of Saturated Soil High Cap Pipe Pile Considering Soil Plug Effect

With the rapid development of China’s infrastructure and construction industry,With the rapid development of my country’s infrastructure and construction industry,pipe piles have been widely used in various infrastructure projects due to their high bearing capacity and low cost.However,the environment where the pile foundation is located is complex,and the dynamic behavior of the pile foundation is related to the safety and stability of the building structure.Therefore,the research on the vibration characteristics of the pile foundation has very important academic and engineering application value.In this paper,considering part of the soil plug effect,based on the virtual soil pile model,the vibration law of saturated soil-high-capped pipe piles is deeply studied,and numerical examples are used to analyze the influence of various parameters on the pile top complex stiffness and horizontal dynamic impedance.The purpose is to reveal the dynamic interaction mechanism of piles and soils,which can be used to guide the anti-seismic and shock-absorbing design of pile foundations and non-destructive testing of foundation piles.The main contents are as follows:（1）Under the premise of considering partial soil plug effect,the vertical vibration of saturated soil-high-cap friction pipe pile is studied.Only considering the vertical displacements of the saturated soil layer around the pile,the saturated soil layer of the pile core and the saturated soil at the bottom of the pile,the forces of the saturated soil around the pile,the saturated soil at the core of the pile and the saturated soil at the bottom of the pile on the pipe pile of unit thickness are obtained,and the On this basis,the vertical vibration control equation of saturated soil-high-capped pipe pile considering the partial soil plug effect is established,and the complex stiffness of the pile top is obtained by using the transfer matrix method.The results of numerical examples show that the inner radius of the pipe pile increases,the wall thickness of the pipe pile becomes thinner,and the vibration curves of the real and imaginary parts of the complex stiffness of the pile top are relatively stable.（2）Considering only horizontal displacement and circumferential displacement,the horizontal dynamic effects of saturated soil around the pile,saturated soil in the pile core and saturated soil at the pile bottom on the pipe pile are obtained by means of mathematical physics.On this basis,the horizontal vibration of saturated soil-high cap friction pipe pile is solved by using the initial parameter method and transfer matrix method,and the horizontal dynamic impedance of the pipe pile is obtained.Numerical examples show that the horizontal dynamic impedance fluctuation peak increases with the increase of shear modulus ratio of pipe pile to soil,and the horizontal dynamic impedance decreases with the increase of modulus ratio of soil around pile.（3）Based on the calculated force of saturated soil around the pile,saturated soil in the pile core and virtual soil at the bottom of the pile on the pipe pile,the dynamic stiffness and dynamic damping of saturated soil high cap pipe pile group considering partial soil plug effect are studied by using the superposition principle and saturated soil pile pile vertical interaction factor,and the numerical analysis program is compiled by MATLAB software.The numerical results show that the curve fluctuation of vertical dynamic impedance of pile group decreases with the increase of pile spacing.（4）Based on the horizontal single pile vibration model of saturated soil-high cap pipe pile with partial soil plug effect,the attenuation function of free field displacement in saturated soil is obtained by using the wave and superposition principle of saturated soil,and the pile-pile horizontal dynamic interaction factor and pile group horizontal impedance in saturated soil are studied.Pile spacing has a great and complex effect on the horizontal impedance of pile group,and the wall thickness of pipe pile also has a great effect on the horizontal dynamic impedance of pile group.Therefore,it should be noted that the wall thickness of pipe pile should not be too thin in engineering.