Study On Vibrations Of Subsoil And Foundation Under Dynamic Machine

Along with the rapid development of industrial technology and social and economic of our country, as the super high pressure compressor, the high speed turbine, and so on, the large dynamic machine apply more and more common. The large dynamic machine needs a stable foundation to support, so the design of dynamic machine foundation has become important part of the whole factory designing. Its standards of designing meet the requirements in many ways,(such as environmental protection and industrial layout, etc), so it limits strictly frequency of foundation vibration. Dynamic machine can produce the bigger vibration in the operation; the excessive vibration will affect normal operation of some instruments and equipment, and also affect the surroundings. So the design of machine foundation must be reasonable, and it must make possible vibration displacement limit in normal work within the scope of the permit.This paper references to the relevant literature of domestic and foreign, and bases on the research results of previous researchers, the following research: first, according to the theory of elastic half space to establish wave equation, and then based on the integral transform(Hankel transform and inverse transform), and combine with the boundary conditions to derive equation of motion of vertical vibration about ground on the surface of the half space. Secondly, base on the basic theory of the elastic dynamical and use Fourier transform theory, derive two-node and a single-node spectral element; then consider completely continuous between the layers to establish the whole stiffness matrix of n layer soil structure, and study the problem of dynamic response of layered soil under dynamic load. Finally, the paper conducts dynamic analysis of dynamic machine foundation and subsoil collaborative work:(1) analysis the dynamic parameters of subsoil, and make the calculation of the dynamic parameters of subsoil using practical method of elastic half-space calculation mode, and then compare its results with the results that obtained under specification states;(2) build finite element model to do dynamic analysis of dynamic machine foundation and subsoil collaborative work.Through the above research, this paper obtains the equation of motion of the machine foundation vertical vibration; derives the single node spectral unit and double node spectral unit, it is concluded the influence discipline of the vertical displacement each point on bottom of foundation in different underlying modulus and different thickness and different loading frequencies; it is concluded the importance of machine foundation and subsoil work together on the design of the machine foundation according to the interaction analysis of between the machine foundation and subsoil; it is concluded that show the frequency characteristics of the maximum vibration linear displacement according to dynamic analysis of machine foundation and subsoil, and can infer that the dynamic machine may occur resonance region in normal work, and make the external incentives from the resonance region as possible, and avoid to appear the resonance.