Calculated Response of Pile Supported Machines


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Title: Calculated Response of Pile Supported Machines

Author(s): Gerald M. Diaz and Mir Azizi

Publication: Special Publication

Volume: 78


Appears on pages(s): 199-224

Keywords: caps (supports); concrete piles; damping; dynamic loads; foundations; machine bases; measurement stiffness; vibration.

Date: 1/1/1982

Past attempts to analyze pile supported foundations included many simplifying assumptions regarding the pile-soil impedence functions (stiffness and damping) for a single pile. Further simplification was required to evaluate the effects of the pile group. In recent years significant studies relating to pile-soil dynamic behavior have been made and good agreement was reported in comparison with relatively small scale field tests. Also, generalized analyses of pile groups have been developed. In this paper the authors have used what they consider to be the current State-of-the-Art techniques for evaluating pile-soil impedence functions, group behavior, and embedment effects to calculate the dynamic response of pile supported machines and compared the calculated results to actual field measurements. Three similar operating plants, each using an identical reciprocating large compressor, were the basis of the study. The soil investigations included in-situ measurement of dynamic properties. The soil conditions at the sites were such that all sites required pile foundations and different pile types, including friction and end bearing piles, and batter piles. The results indicate that good agreement is achieved using the methods proposed for the rocking, and horizontal and vertical translation modes of vibration. .Further analyses are recommended to further investigate the behavior in the torsional mode. Also, further comparisons should be made with actual foundations where vibrations could be monitored at varying frequencies.