Experimental Study On Environmental Vibration Reduction Measures In Urban Rail Transit

Urbanization is the inevitable trend of the common development of all countries in the world.In the process of realizing urbanization,in order to solve the problems of urban transportation and make up for the shortage of urban transportation,urban rail transit,with its advantages of high efficiency,high speed and high comfort,has become the first choice of major cities and attracted great attention in the industry.However,the resulting environmental vibration problems have affected many fields.With the increasing density of rail transit industry and load concentration,the problem of environmental vibration pollution is becoming more and more prominent.In our country,the environmental vibration caused by rail transit not only affects the daily activities of nearby residents,but also reduces the stability of buildings along the line and the accuracy of scientific research equipment.Therefore,it is the focus of many scholars to find out the causes of vibration and the methods and measures to control vibration propagation.In order to avoid large-scale demolition of existing buildings along the route,it is proved that it is an effective way to set up a vibration barrier between the vibration source and the protected object.On the basis of this principle,this paper adopts the method of linear analysis and the vibration acceleration grade VAL as the evaluation standard to compare and analyze several common vibration isolation barriers to judge the vibration isolation performance of each barrier.Furthermore,using the simple form of isolation barrier to expand the maximum pile barrier,using the combination of linear analysis and regional analysis to analyze the change of the effective vibration isolation area after the barrier,the vibration isolation performance of the multi-row pile is studied in depth.In this paper,the following conclusions are drawn:1.Propagation law of vibrational wave in free fieldAt the same vibration frequency,the vibration of the surface decreases with the increase of the propagation distance of the vibration wave.At the same time,it is found that with the increase of the propagation distance,the decay and deceleration rate of the high frequency vibration wave is gradually accelerated,and the contribution rate to the surface vibration is low,and the middle and low frequency vibration is the main cause of the remote surface vibration.2.Typical isolation barriersIn the continuous vibration isolation barrier,the empty ditch,underground continuous wall and filling ditch can be used as a whole to block the vibration wave,and the vibration isolation effect of the empty ditch is the best.At the same time,the vibration isolation effect of filling material in filling ditch is different,and in this paper,the vibration isolation effect of underground continuous wall is obviously better than that of gravel powder and rubber particle filling ditch.This shows that the barrier of the rigid material to the vibration wave is more obvious in the whole state.At the same time,the vibration isolation performance of rigid filling material is better than that of flexible filling material.Among the non-continuous vibration isolation barriers,the isolation effect of single row solid concrete pile is more PVC than that of empty well,and the empty well filled with crushed stone powder and rubber particles will not improve its vibration isolation effect;the smaller the cross section hollow ratio of concrete pile,the better the vibration isolation effect is.However,with the increase of vibration wave propagation distance,the influence of section hollow ratio on vibration isolation effect of concrete pile is smaller,and the change of internal and external section shape of concrete hollow pile will also affect the vibration isolation effect,and the influence of external section shape is more obvious.3.Multiple Pile BarrierCompared with single and double row piles,the vibration amplification in front of three row piles is more obvious,and the uniformity of vibration reduction in the postpile area is also obviously improved.In practical engineering,the ratio of the net distance between piles and the edge of piles should be controlled to be less than 1.5,and the change of net distance between rows has little effect on the isolation effect of multi-row pile barriers.