The Low-frequency Vibration Analysis Of Subway Under Different Vibration Isolation Measures

As a low-carbon transportation,the subway has gradually been recognized by the general public.Urban subway construction has been greatly developed in China,and the rapid development of subway travel is the trend of the future subway development.The low-frequency vibration caused by the subway operation has increasingly affected People's Daily life and even some hospitals,laboratories and other precision instruments.In recent years,the low-frequency vibration of subway has been widely concerned at home and abroad,based on the future development process of metro,it is necessary to study effective vibration isolation measures.The vibration reduction measures caused by traffic loads such as ditching and continuous walls in 60 s are studied.The diaphragm wall isolation principle is used as a rigid barrier to prevent vibration propagation.and its vibration isolation effect depends on the depth of the continuous wall.The open trench is to use its barrier wave propagation path.The results show that the groove has little effect on low frequency vibration when the groove depth is less than 30% of the shallow surface wavelength.The construction of open diaphragm wall is very difficult.so the traditional vibration isolation can not meet the vibration isolation effect of the modern subway.Since 1990 s,Schmid proposed the establishment of "artificial bedrock" to shield soil vibration,also known as Wib wave barrier block.Subsequently,Japanese scholar Kobita Kimi Lam made a significant improvement on WIB.and proposed the isolation of Honeycomb Impeding Block(HWIB).The the incident wave is modulated to a shorter wavelength,thus the vibration isolation effect is better,and in which the noise reduction materials can be filled in,it can also absorb the short wave.But HWIB construction is difficult.But construction of HWIB is difficult.In this paper,on the basis of HWIB new type vibration isolation measures-Pile HWIB(running the Honeycomb Impeding Block P-HWIB)isolation,use the method of foundation treatment or soil reinforcement to construct the P-HWIB,both can play the role of row pile and get good vibration isolation effect.First,a numerical model of train,tunnel and ground is established,which simplifies the train load along the tunnel dynamic load series,studies the load reduction effect of the underground continuous wall and open channel,and then studies the relief effect of the solid WIB and the Seine WIB.and then analyzed the vibration isolation effect of different size of the HWIB.Finally,the influence of the parameters such as depth and size of honeycomb on the vibration isolation effect of P-HWIB was studied.The appropriate P-HWIB parameters were determined,and the vibration isolation effect of P-HWIB was obtained.Compared with the vibration isolation measures,the surface acceleration can be reduced by more than 65% and the vibration amplitude can be reduced by more than 70%.For the low-frequency vibration segment within 10 Hz,the P-HWIB has better isolation effect than the continuous wall,open trench and WIB,and the vibration amplitude can be reduced by more than 70%.From the perspective of construction,p-hwib is a honeycomb structure formed directly by CFG pile,which solves the problem of construction and save the cost.Therefore,P-HWIB is an effective method to reduce the vibration isolation of low-frequency vibration.