Design And Research Of Hydraulic Linear Vibration Impact Hammer Test System

With the economic development,pile foundation projects such as artificial islands and sea-crossing bridges are widely carried out in China.Pile hammer equipment is the key equipment in pile foundation engineering.Its working performance is not only related to the work efficiency of the whole project,but also plays an important role in energy conservation.The development of vibratory pile hammers in China is still far behind the developed countries in Europe and America.The famous Hong Kong-Zhuhai-Macao Bridge pile foundation project uses the American APE600 vibratory hammer.Therefore,it is very necessary to study a new type of pile hammer with high energy efficiency.This paper analyzes the existing motor eccentric block vibratory hammer.It generates an exciting force through a pair of counter-rotating eccentric blocks.The horizontal force of the vibration mode cancels each other out,and only the vertical direction force is used for sinking piles,and the energy utilization rate is low.The mechanical structure of the pile hammer is broken and stopped by the resonance zone,and the frequency modulation cannot be performed in real time during the working process,and the work efficiency is low.This paper proposes a new kind of pile-rocking equipment with linear vibration and shock coupling based on hydraulic fluctuation,which uses oil cylinder instead of motor eccentric block to generate vibration.The vibration cylinder moves linearly,there is no waste of horizontal component energy,and energy utilization is improved.Pure hydraulic vibration,the equipment starts and stops very fast,does not cause resonance to damage the mechanical structure,The vibration generating mechanism is the core of the vibration generated by the pile hammer.Therefore,a new vibration generating mechanism is designed,through which the real-time frequency modulation of the vibration impact hammer during the working process can be realized,and the hydraulic shock phenomenon is generated at the same time,and the energy is utilized.Establishing the power bond diagram of the force source and the flow source mode considering the pipeline characteristic vibration and shock test hydraulic system,establish the flow source mode without considering the pipeline characteristics,derive the state equation,use MATLAB for simulation analysis,and obtain the system pressure and flow.The influence of the pipeline on the amplitude of the system.In order to verify the mechanism of the proposed new vibration impact hammer,an experimental vibration impact hammer was designed and the experimental platform was selected and constructed.The hammer vibration experiment under certain parameters was carried out using the vibration test system of LMS Test.Lab.According to the measured time-amplitude curve analysis,it is true that there is an impact phenomenon during the vibration process,and the real-time frequency modulation can be performed by the new vibration generating mechanism during the working process.Replace the hoses of different diameters and analyze the influence of different flow rates on the amplitude of the hammer.The springs with different stiffness were replaced and the vibration curve was analyzed.It was found that as the spring stiffness increased,the amplitude of the hammer head decreased,but the vibration balance position moved down,which was beneficial to the impact.The accelerometer is used to measure the acceleration of the hammer at 15 Hz,29Hz,38 Hz.As the frequency increases,the acceleration increases.The hammer is the carrier of kinetic energy,which can generate more impact force.Therefore,under the requirement of ensuring the amplitude is satisfied.The higher the frequency,the better.The acceleration sensor is attached to the simulated pile body,and the amplitude of the pile body is measured at the vibration frequency of 15 Hz and 38 Hz,which provides a basis for the subsequent study of the optimal system parameters and the optimal impact point position.