Study On The Near Field Wave Vibration Isolation In The Process Of Hammer Piling

The precast pile are widely used in engineering practice because of their easy detection of guaranteed quality,good bearing capacity,high construction efficiency,can be made in advance of the pile work etc.However,the vibration,soil squeezing and noise generated during the construction of precast piles will have a great impact on the surrounding environment.In order to reduce the harm,we choose a certain type of pile hammer,hammer weight,falling distance,piling frequency and other parameters.In addition,in order to reduce the impact of vibration,we often set barrier isolation before the object to be protected and use the reflection and diffraction of the barrier to lose energy.According to the theory of elastic wave and barrier isolation mechanism,the formula for calculating the critical frequency of barrier anastomosis is derived.The feasibility of the formula is verified by a numerical example.Secondly,this paper analyzes the important factors that affect the vibration isolation of the vibration isolation trench,and puts forward the general structure of the parameter analysis scheme,and uses LS-DYNA software to establish the dynamic model of pile and soil.Finally,the effects of various parameters on the vibration isolation effect are discussed,including the depth of the vibration source,the size of the vibration isolation trench,the location of the vibration isolation trench,the properties of the foundation soil and the material of the vibration isolation trench.In this paper,the failure of vibration isolation trench is discussed,and the abnormal phenomenon of amplitude amplification and the factors that affect the amplitude magnification are studied.The results showed that within a certain range of vibration isolation trench depth,the greater the trench depth,the vibration isolation effect is better;The influence of width for the vibration isolation effect is small;Near the isolation trench position of vibration isolation effect is relatively good,general for a location near the trench after 6 m;Within a certain range of soil shear wave velocity is larger,the better the effect of vibration isolation;The greater the difference of the wave impedance between the material and the soil,the better the vibration isolation effect.The deeper the vibration isolation ditch is,the stronger the strengthening effect is and the greater the scope of the reinforcement area is.The wider the vibration isolation ditch is,the smaller the strengthening effect of the reinforcing area is,and the smaller the reinforcing area is.The farther away from the vibration source,the smaller the strengthening effect of the amplitude enhancement area,The scope of the strengthening area showed a trend of decreasing first and then increasing;Larger soil shear wave velocity can reduce vibration isolation trench in the probability of failure;Wave impedance of similar vibration isolation trench material,its strengthening effect and strengthen regional also similar.