Numerical Simulation Research On Vibration Absorption And Isolation For The Foundation Of High-precision Centrifuge Base

With the development of modern high-precision instruments,the requirement of test accuracy is higher and higher,the prevention and control of site micro-vibration has become an urgent problem to be solved.This paper relies on the subject of vibration reduction and vibration isolation of the foundation of a precision instrument,uses vibration acceleration as the control index,and uses the finite element software ABAQUS to reasonably construct the three-dimensional model of the foundation of the high-precision centrifuge base,and the influence of different design parameters on the vibration reduction and isolation effect of centrifuge foundation under the proposed site micro-vibration load is analyzed,and provided suggestions for the actual engineering construction.The main research contents and results of this article are as follows:1.By performing spectrum analysis on the calculation results of different model parameters under the site micro-vibration,it is found that when the effective value of the acceleration obtained by the maximum model size is an accurate value,the relative errors generated by the remaining models are basically controlled within 5%;For this project,the circular boundary is more reasonable than the square boundary,and the calculation result is more conservative;The calculated acceleration amplitude and acceleration effective value both decrease with the decrease of the grid element size,and tend to be stable.2.The impact of changing the foundation depth on the vibration reduction effect is related to the way of simultaneous loading on the ground and 20m below the ground.Under the action of the site micro-vibration used in this article,the best vibration reduction effect is obtained when the foundation depth is 8m.3.The vibration isolation effect of the open ditch is better than that of the concrete barrier;Using high-strength concrete barriers will not significantly improve the vibration isolation effect.4.Increasing the depth of the barrier within a certain range makes the vibration isolation effect generally increase,and increasing the thickness of the barrier can improve the vibration isolation effect.However,with the increase of the depth and thickness of the barrier,the vibration isolation effect no longer changes significantly.5.When the foundation radius is consistent,the vibration reduction effect generally tends to increase with the increase of the foundation height,and the larger the foundation radius is,the more obvious the improvement trend is;When the foundation height is consistent,the increase of the foundation radius can effectively improve the vibration reduction effect,and the higher the foundation is,the vibration reduction effect is more obvious with the increase of foundation radius;Keeping the foundation height the same,the vibration damping effect of the circular foundation is better than the square foundation under the same quality;The vibration reduction effect of different foundation forms is from good to poor in order:pile foundation combined with concrete foundation cushion,concrete foundation cushion,and sand with the same volume as the concrete cushion.6.Under the action of the vibration reduction and isolation system of"vertical barrier+deep foundation+concrete foundation platform+concrete foundation cushion+pile foundation",compared with the vibration source,the acceleration amplitude of the centrifuge foundation is attenuated by 1-3 orders of magnitude.The frequency band of the amplitude spectrum is 0Hz-10Hz.The maximum amplitude and the effective value of the acceleration are less than"2.5×10^-6g"required by the design.