Study On Vibration Wave Barrier Mechanism Of Concrete Pile Row In Layered Foundation

The development of urban traffic improves people’s living standards while exposing more and more problems.The vibration not only seriously affects the quality of life and daily life of nearby residents,but also reduces the accuracy of some precision instruments.In this regard,many related scholars are studying the causes and solutions of vibration.In this thiese,the influence law of pile length,buried depth and pile spacing on vibration isolation effect is studied by using the control variable method,and the coupling model of "track-subgrade-foundation" is established to further study the vibration effect of concrete pile row under the condition of train movement.Taking the amplitude reduction ratio Ar and the proportion of effective vibration isolation area as evaluation indexes,the following conclusions are drawn based on the conditions in this thesis:(1)Through the test,it is found that when the pile length parameter is between0.047 and 0.660,the vibration isolation effect of pile row becomes better with the increase of pile length parameter.When the pile length parameter is 0.472,the vibration isolation effect is better.When the pile spacing parameter increases from 0.024 to 0.142,the ratio of effective vibration isolation area decreases by 17.0%,and the vibration isolation effect weakens with the increase of pile spacing.Therefore,concrete piles should be arranged more closely.When the buried depth is between 10 cm and 25 cm,the vibration isolation effect of the concrete pile row is weakened with the increase of the buried depth,but the concrete pile row will show a sudden change at the soil layer interface.The concrete pile layout should avoid the interface as far as possible and be shallower.(2)A 1:1 site model was established in the finite element software.By comparing with the results of the field test,it was found that the Ar value variation trend under the finite element calculation was basically consistent with that in the test,so the finite element software could be used for further research(3)The "track-subgrade-foundation" coupling model is established,and it is found that the area of effective vibration isolation increases with the increase of pile length parameter.When the value of pile length parameter is 7.7,both the subgrade slope and the foundation surface achieve good vibration isolation effect.When the value of the buried depth parameter decreases,the vibration of the subgrade slope and the foundation surface is weakened,and the concrete pile plays a good vibration isolation effect.When the buried depth parameter is 4.2,the effective vibration isolation area of the foundation surface is only 3.08%,and the concrete pile almost loses the vibration isolation effect.When the value of pile spacing parameter decreases,the vibration at subgrade slope and foundation surface is weakened.When the pile spacing parameter is 3.5,the peak value of vertical acceleration at subgrade slope is not much different from that without vibration isolation,and the proportion of effective vibration isolation area at the foundation surface is only 1.26%.At this time,the concrete pile row almost loses the vibration isolation effect.(4)After the concrete pile row is arranged,the vibration isolation effect in the depth of the foundation is worse than that in the shallower part,and the effect of vibration enhancement will appear at the boundary of the soil layer.The increase of the pile length parameter makes the vibration isolation effect of the concrete pile enhanced,but the increase of the buried depth parameter and pile spacing parameter will weaken the vibration isolation effect.