Experimental evaluation of the effect of soil water fluctuations in the dynamic behavior of machines

摘要

In this study the dynamic response of a machine-foundation-soil system was investigated experimentally and theoretically. The objective of this work is to analyze the effects of the water table fluctuations in the soil on the response of the foundation and machine subjected to dynamic loads at frequencies ranging from 30 to 50 Hz. A physical model test was developed to simulate a machine-foundation-soil system, with measurements of the machine vibrations and the shear wave velocity of the soil. It is found that the water level produced significant changes in the shear wave velocity of the soil and, thus, in the natural frequencies of the system. For a fully saturated soil the vibration levels increased due to a working condition near resonance. The results showed a good agreement between the experimental vibration measurements and the predictions based on the theory used in foundation design, when considering the appropriate soil parameters. It is concluded that proper estimation of soil parameters is of high importance in the design process of machine foundations.