WIT Press

Replacement Of Rigid Soil By An Elastic Material For The Reduction Of Sensitive Machine Vibrations


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G. Rosenhouse, F. Kirzhner & Y. Zimmles


Elastic mountings are necessary for reducing the effect of environmental vibrations on sensitive machinery. The common method is the application of artificial polymeric, fibrous materials or metal springs as elastic mountings. Such mountings necessitate control and maintenance. It is much more attractive to use materials that do not deteriorate over time, at least for a few decades. This is due to the fact that in order to get the effect of "mass-spring" response, a heavy mass that supports the sensitive system is laid over an elastic material. At least a partial solution can be obtained by soil replacement of the rock underneath the foundation. However, it is illustrated here numerically that the result is strongly dependent on the spectrum of the system response, and in certain cases incorrect design may even cause weakening of the isolation. Keywords: soil mechanics, elastic isolation, soil replacement, vibrations, spectral response. 1 Introduction Regular design of foundations isolation considers the natural properties of the existing ground. However, under certain circumstances, the ground, on which the foundation is intended to be built, is too hard and/or non-uniform. In the first case the protected machine may suffer severe vibrations that are beyond its capacity, or may lead to damages, such as defects in the products of the machine. In the second case, the non-uniformity of the ground under the foundation can lead to differential settlement, cracks in the structure and even instabilities. A change in the mechanical properties of the soil under the foundation can be used


soil mechanics, elastic isolation, soil replacement, vibrations, spectral response.