Study On Mechanism Of High-frequency Hydraulic Vibration Sinking Of Steel Pipe Pile In Saturated Sand Layer

The high-frequency hydraulic vibration pile-sinking technology of engineering piles has been widely applied in the geotechnical engineering construction field due to its advantages of high pile-driving efficiency and good environmental protection efficiency.However,at present,the relevant research on high-frequency hydraulic vibration pile-sinking mechanism and technology at home and abroad is not yet completely clear.Therefore,this dissertation relies on the high-frequency hydraulic vibration pile-sinking engineering example of steel pipe piles in the original reconstruction project of Kunming Textile Factory in Yunnan Province.Through on-site investigations,indoor geotechnical tests,and three-dimensional dynamic finite element numerical simulation based on Midas GTS NX,DPS data processing,and GTMS grey correlation analysis,the mechanism of high-frequency hydraulic vibration pileinsucking of steel pipe piles in saturated sandy soil layers was studied.The aim is to further reveal the mechanism of high-frequency hydraulic vibration pile sinking of steel pipe piles and optimize the pile-sinking process.The main research contents of this dissertation are as follows:(1)The mechanism and process of high-frequency hydraulic vibration pile-sinking are investigated,and the pile-sinking test,theory and numerical simulation of high-frequency hydraulic vibratory hammer sinking are understood;(2)The high-frequency hydraulic vibratory hammer is analyzed and studied.(3)Conducting corresponding surveys and indoor geotechnical tests for the original site reconstruction project of Kunming Textile Factory;(4)Establishing high-frequency hydraulic vibration pile sinking for steel pipe piles based on the large-scale 3D finite element analysis software Midas GTS NX.The threedimensional dynamic finite element model of the process uses dynamic time history analysis method to study the distribution of displacement field,velocity field and acceleration field of steel pipe piles under high-frequency hydraulic vibration under different working conditions;(5)based on three-dimensional dynamic finite Based on the numerical simulation,using orthogonal analysis and grey relational degree theory,the sensitivity of the parameters such as excitation force,vibration frequency,soil parameters and pile diameter of steel pipe piles in high-frequency vibration pile displacement of steel pipe piles was analyzed.The process parameters of highfrequency vibration pile sinking of steel pipe piles were optimized.The results of the dissertation show that:(1)During the high-frequency vibration pile sinking of steel pipe piles,with the deepening of steel pipe piles,the lateral frictional resistance between piles and soils increases,resulting in a decrease in the pile displacement of steel pipe piles..(2)The high frequency vibration of steel pipe piles will cause slight vibration of the surface soil around the pile during the process of penetration into the soil.With the deepening of steel pipe piles,the vertical disturbance range of the surface soil layer around the pile gradually increases,but the disturbance of the surface soil decreases with the distance from the steel pipe pile.(3)When the steel pipe pile first sinks into the soil,the movement speed of the pile end is relatively large,but the subsequent pile sinking speed is constantly attenuated;during the high frequency vibration pile sinking of the steel pipe pile,the acceleration of the pile end of the steel pipe pile It decreases as the depth of the pile penetrates into the soil.(4)During highfrequency hydraulic vibration pile sinking of steel pipe piles,the pile displacement increases with the increase of the excitation force,decreases with the increase of the vibration frequency,and decreases with the increase of the pile diameter of the steel pipe pile,and the displacement of the pile sinking.As the dynamic elastic modulus of the soil increases,it decreases.(5)In the process of high-frequency hydraulic vibration pile sinking of steel pipe piles,the best correlation of the pile value is the excitation force exerted by the high frequency vibration hammer,followed by the vibration frequency,and the third is the pile diameter of the steel pipe pile.Finally,the dynamic elastic modulus of the soil.The main innovations of the dissertation are as follows:(1)Based on DruckerPrager criterion,the Coulomb friction contact interface between pile and soil is set up.Three-dimensional finite element software Midas GTS NX is used to carry out threedimensional dynamics of high-frequency hydraulic vibration pile sinking of steel pipe pile;(2)Based on three-dimensional dynamic finite element numerical simulation,using orthogonal analysis and grey relational degree theory,the exciting force,vibration frequency,soil parameters,and steel that affect the high-frequency vibration pile displacement of steel pipe piles are calculated.Sensitivity analysis was performed on parameters such as pipe pile diameter,and the process parameters of high-frequency vibration pile sinking of steel pipe piles were optimized.