Analysis Of Collision Process And Research On Leakage Suppression Of Hydraulic Piling Hammer

In recent years,hydraulic piling hammer has become the main force of pile machinery due to its excellent performance.The hydraulic pile driver relies on the potential energy impact of the hammerhead to penetrate the pile into the soil layer.This working feature results in high hydraulic vibration and impact in the main oil circuit,which can easily cause hydraulic components to leak and become damaged.Pile hammer structural components are also prone to failure due to impact.A simulation model was established to analyze the change trend of the hammer head stress under different structural parameters of the pile hammer during the collision process.The influence of pipeline structural parameters on pipeline leakage was studied based on fluid-solid coupling analysis.Several structural parameter optimization schemes were proposed.To design a high-frequency,high-impact energy,and impact-resistant double-acting hydraulic pile driver,optimization was carried out on the basis of the traditional hydraulic system.According to the optimized schematic diagram,a design scheme for an integrated cylinder head block was proposed,and key system parameters were calculated.According to the working process of the hydraulic pile hammer,the mathematical modeling of the hydraulic system is carried out on the rising stage,falling stage and pressure maintaining stage of the pile hammer,so as to provide reliable data for the subsequent analysis work.Multibody dynamics software was used to establish a model of the hammerhead-pad layer-pile cap-pile-soil layer.By analyzing the stress cloud diagram of the model,the stress distribution rules in the model were revealed.The stress changes of the hammerhead’s key points under a single collision were analyzed,and the influence of the model’s structural parameters on the key point stress was explored.Through simulation analysis,it was found that the hammerhead stress was greatly affected by the hammer pad stiffness,pile pad stiffness,hammerhead impact initial velocity,and hammerhead mass,while the effect of pad layer damping was relatively small.It helps to reduce the risk of damage to the hammer head and improve the service life of the structural parts of the pile hammer.For the pipeline of the cylinder head integrated block with the most severe hydraulic leakage,CFD(Computational Fluid Dynamics)software was employed for fluid-solid coupling analysis.High-quality grids were established,and the flow rules of hydraulic oil in the pipeline were summarized through pressure cloud maps and pressure vector diagrams.The effects of O-ring compression ratio and pipe wall thickness,two structural parameters,on pipeline sealing performance were investigated.Through simulation analysis,it is found that under high pressure conditions,appropriately increasing the compression rate and reducing the inner diameter of the pipeline will reduce the workload of the seal and enhance the sealing performance of the pipeline.This study revealed the influence of structural parameters on hammerhead stress and pipeline sealing performance during the collision process between the hammer and the pile body,providing guidance for the optimization of hydraulic pile driver structural parameters.