Experimental Research On Vibration Isolation Performace Of Rectangular Vibration Isolation Groove

Since the beginning of the 21 st century,artificial vibration problems caused by building tamping and rail transit have caused great troubles to people’s production and life.It not only affects the health of nearby residents,but also affects the normal use of precision instruments and sensitive buildings.Negative effects that cannot be ignored.In order to reduce the adverse effects of artificial vibration,it is necessary to understand the propagation law of artificial vibration in the soil medium,and take corresponding measures to isolate and prevent the vibration.After a century of research and exploration,vibration isolation barriers are considered to be the most effective,economical,and convenient form of vibration isolation,which can be divided into discontinuous vibration isolation barriers and continuous vibration isolation barriers according to their structural form.Continuous vibration isolation barriers are easier and more convenient to construct than discontinuous vibration isolation barriers,and it is particularly economical to excavate trenches for vibration isolation.In this paper,based on the vibration wave propagation law and attenuation characteristics test in the sand foundation,further,the vibration isolation performance of the rectangular vibration isolation trench is studied from a one-dimensional perspective,and the rectangular vibration isolation trench is analyzed from a two-dimensional perspective combined with one-dimensional linearity.The vibration isolation area range of the groove clarifies the vibration isolation mechanism of the rectangular vibration isolation groove.In the research process,on the one hand,this paper studied the attenuation law and propagation characteristics of the vibration wave in the sand foundation by testing the acceleration amplitude of the sand foundation surface.The results showed that:When the vibration wave propagates in the sand foundation,under the same condition of the excitation frequency of the vibration source,as the propagation distance increases,the energy of the vibration wave is consumed by the damping of the soil itself,which makes the vibration acceleration amplitude of the foundation surface gradually decrease;Low-frequency vibration waves are the main cause of soil vibration.When it propagates in the sand foundation to 100 cm,the energy of the vibration waves is attenuated by approximately 64.46%.The contribution rate of medium and high-frequency vibration waves to the surface vibration is relatively low.The distance is relatively short.On the other hand,in order to clarify the influence of different rectangular vibration isolation groove sizes and Rayleigh wave wavelength parameter ratios on the vibration isolation area behind the groove,the acceleration amplitude of the free foundation and the corresponding control points when the rectangular groove is set are measured through field tests.Draw a two-dimensional plane contour map about the ratio of the two,take the area with the ratio of the two not greater than 0.4 as the vibration shielding area,and analyze the area of the vibration shielding area as the evaluation index of the vibration isolation effect,and get the following conclusions:First of all,when Rayleigh waves propagate in sandy soil foundations,energy redistribution occurs when they encounter a trench barrier.Except for the part of the energy consumed during the propagation of the vibration wave,part of the remaining energy is bounced back by the trench.,The other part breaks through the barrier of the trench through wave diffraction,transmission,etc.,and continues to propagate forward;Secondly,the rectangular groove depth parameter,length parameter,distance parameter and the logarithm of the vibration shielding area are linear,limited to the test conditions in this article,when the range of D value,L value,and E value is0.53～0.75,1.11,respectively ～1.52,0.78～1.13,the vibration shielding area does not change significantly;the ratio of the width of the rectangular groove to the wavelength of the Rayleigh wave has little effect on the vibration shielding area,and there is a linear relationship between the two;Finally,the normalized cross-sectional area of the rectangular groove has a greater impact on the vibration isolation effect.As the normalized cross-sectional area increases,the vibration isolation effect becomes better and better.Limited to the conditions in this article,when the value of N is in the range When it is 0.02～0.78,increasing the distance parameter can significantly increase the area of the vibration shielding area.