Study On Soil Modeling And Vibration Isolation Of Micro-vibration Foundation Under Harmonic Load

With the mass production of various high-tech industrial precision products,a large number of high-tech electronic factories have been built.The high-tech electronic factories has a higher demand for micro-vibration than the traditional industrial factories,so the design of micro-vibration control is essential to ensure the normal use of precision instruments in the electronic factories.The problem of micro-vibration of high-tech electronic factories is very complex,in which the propagation path and attenuation law of wave in the foundation are the preconditions for micro-vibration design of electronic factories.Firstly,the principle of soil modeling and the influence of several parameters on the response of soil surface vibration are studied,which provides theoretical modeling principles for vibration isolation design of electronic factories.Secondly,the vertical vibration reduction effect of the micro-vibration foundation is further studied based on the above research results,which provides the basis for the application design of micro-vibration foundation in high-tech electronic factories.The conclusions are as follows:A two-dimensional axisymmetric soil model is established to study the selection principles of mesh size,artificial boundary and model size.The conclusions are as follows:1)The reasonable discrete mesh size should be?7?1/9¹/6?8??_{m in};2)The length of the foundation model is suggested to be at least 3 times the wavelength plus the distance between the observation point and the vibration source,and the thickness of the model is suggested to be at least 2 times the wavelength plus the distance between the observation point and the vibration source;3)The viscoelastic artificial boundary can simulate the truncated boundary of the foundation model,and has higher simulation accuracy than the fixed boundary and the viscous boundary.Based on the above modeling principles,the influence of different parameters on the vibration response of soil surface is studied by establishing the soil model.The results are as follows:1)The vibration response of soft soil attenuates faster than that of hard soil;2)The initial vibration response of soft soil is larger than that of hard soil,so although the response of soft soil attenuates faster,the vibration response of soft soil may still be larger than that of hard soil in far field;3)The density of soil has no effect on the attenuation of vibration response;4)The vibration response attenuates faster than that of soil with large damping ratio.Based on the above modeling principles,the influence of foundation size and material parameters on vertical vibration reduction effect of micro-vibration foundation under harmonic load is studied by establishing the micro-vibration foundation model.The results are as follows:1)The length of foundation has little effect on the vertical vibration reduction effect;2)The vibration reduction effect of micro-vibration foundation at high-frequency is better than that at low-frequency;3)Increasing the thickness of foundation can improve the effect of vertical vibration reduction,but the effect of vibration reduction is not obvious after increasing a certain thickness;4)The distance between the boundary of the foundation and the vibration source has little influence on the vertical vibration isolation effect;5)The vertical vibration reduction effect of the micro-vibration foundation on the soft foundation is better.Because the initial vibration response of the soft foundation is large,so the surface vibration response of the soft foundation in the far field may be greater than that of the hard foundation;6)The density of soil is not too sensitive to the vertical vibration reduction of micro-vibration foundation.