Research On Performance And Design Method Of Hydro-pneumatic Driving Pile Hammer With Impact Energy And Frequency Adjusted Steplessly

With the advantages of no exhaust gas, high energy efficiency and working process easily controlled, hydraulic pile hammer has been applied more and more widely in pile foundation. The domestic theory of hydraulic pile hammer falls behind and there are no mature products of our own; in overseas, their products are much more mature, however, the small adjustment rang of impact energy and frequency limit the promotion and application of hydraulic pile hammer.Contrapose the theory and technology shortcoming of hydraulic pile hammer in design and application, combining science and technology project of HuNan province, aiming at research on performance and design of hydraulic pile hammer with energy and frequency adjusted steplessly, designs the hydro-pneumatic system with energy and frequency adjusted steplessly; establishes four-sect design method for hydro-pneumatic pile hammer through analysis of movement characteris-tics; goes into the research on the key part (main control valve) in flexible control technology and the pile detaching protect system with impact energy reducing and absorbing technology. The main research work is as follows:Firstly, the research and development of hydraulic pile hammer, their design method and key technologies at home and abroad are analyzed, breaking through the limits of impact energy and frequency adjustment, the structure and design rules are confirmed; the hydro-pneumatic driving scheme with pile detaching protect is designed, which adopts pressure feedback control and main control valve to realize flexibly reversing of pile hammer with impact energy and frequency adjusted steplessly.Secondly, four-sect design method for hydro-pneumatic pile hammer is researched. On analysis of movement characteristics for the hammer, dividing the movement into ascend acceleration, ascend regular moving, descend deceleration and descend acceleration, introducing the time ratio γt, of movement period to descend acceleration time, and the velocity ratio αv of maximum ascend velocity to maximum descend velocity, a whole four-sect design method is formed; Then, the researches on the key part (main control valve) in flexible control technology and pile detaching protect system with hydraulic control are done. Firstly, the main control valve is designed. The dynamic mathematic model and simulation model of the valve reversing are established. The effect rules of structure parameters to the performance of the valve reversing are researched, and the valve is optimized with robust design method; Then, the pile detaching protect system with hydraulic control is designed.The static design method for pile detaching protect absorb machine is proposed. The dynamic mathematic model and simulation model of the absorb machine are established with thermodynamics and hydrokinetics rules, and the effect rules of relative parameters to its performance are researched.Then, the performance of the hydro-pneumatic hammer designed is simulated. The mathematical models of impact cylinder, main control valve, cartridge valve and pile hammer impact system are derived through the analysis of mechanism. Combining Simulink and AMEsim, the simulation model of hydraulic control system and pile hammer impact system are established. By simulation analysis, the effect rules of nitrogen initial pressure, control pressure of hammer descend and system supply oil to performance of hydraulic pile hammer is found. The effect rules of the equivalent parameters for filled metal particles and cushion parameters to impact system performance are also found.Finally, the performances of hydraulic pile hammer and pile detach protect absorb machine are tested and analyzed in prototype aeroplane, and also the piling resistance. The results proved that the design theory and simulation model of hydraulic pile hammer are correct, and also the design method and simulation model for pile detach absorb machine.The researches above forms a design method for hydro-pneumatic pile hammer, which supply a theory foundation to hydro-pneumatic pile hammer technology.