Dynamic Characteristic Analysis And Simulation Of Experimental Prototype Of Vibratory Pile Driver

With the continuous development of high building industry, technical requirement of pile foundation in construction gets more and more strict. Because of the limitations of working principle, traditional static piling construction technology faces some challenges. However, new vibratory pile drivers have been becoming the future important matter of research and development with its unique properties and advantages. Although some mature products have been produced in abroad, the research on sinking theory, sinking resistance, and the dynamic characteristics of products is far from enough. It brings some restraining effect on construction quality, sinking efficiency and construction costs.This paper takes experimental prototype of vibratory pile driver as the research object, bases on the basic principle of mechanics, tribology and nonlinear vibration theory and studies dynamic characteristics of the pile driver by the means of theoretical deducing, dynamic simulation, finite element analysis and experiment. The main contents of this paper can be summarized as following:(1) Studying from ultimate dynamic stress state and shear limit dynamic strength theory when sinking, this paper has established a mechanics model of shearing dynamic stress of pile end soil and derived the analytical expression of required pile tip resistance and side frictional resistance if piles can sink into the soil. Based on this, this paper has made analysis on the dynamic action of experimental prototype of vibratory pile driver, built the dynamic model on pile-soil system, established dynamic equation of vibratory pile driver system, and finally got the analytical solution of the model by means of nonlinear vibration theory method.(2) On the basis of dynamic model, the dynamic simulation analysis of experimental prototype has been taken using modeling simulation software AMEsim. Pile driver dynamic characteristic has been studied on certain vibration frequency and under different sinking environment. Besides, the trend that sinking displacement, sinking rate, pile tip resistance and pile side frictional resistance change with time has also been analyzed. Significantly, the nonlinear characteristics of pile tip resistance and pile side frictional resistance on pile-soil contact surface is researched.(3) Finite element model of experimental prototype of vibratory pile driver is established, its dynamic characteristic is analyzed and the first fourth-order natural frequency and vibration modes of complete machine is worked out.(4) Pile driver prototype is taken as the research object. By means of experimental modal analysis technology, two experiment solutions that using guide rod and not using are adopted, and finally the natural frequency and vibration modes in0-400Hz are worked out. The first sixth-order vibration modes are described especially, taken to contrast with the result of finite element analysis and made for finding out the reason for error. The contrasting analysis indicates that the third vibration mode of finite element analysis represents a bigger difference with the facts. Consequently, in actual working, the third vibration mode should be consult with experiment results.