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Combined massive and plate foundations under machines with dynamic loadings
Des fondations combinées à blocs et plaques pour des machines avec charges dynamiques
Kirichek Y., Bolshakov V.
Pridnipronsk State Academy of Civil Engineering and Architecture
ABSTRACT: A new type of foundation under machines with dynamic loading is presented. The combined massive and plate
foundation consist of deepened rigid solid mass and attached thin horizontal plates. Finite element analysis of the combined massive
and plate foundation under machines with periodic loading is conducted. The analytical method of dynamic analysis of combined
massive plate foundations under impact, rotating and reciprocal machines under dynamic loadings is applied. Experimental
investigation of the combined massive and plate foundation interaction with a soil base was performed on large-scale models in the
open ground. The analytical and numerical results are compared with large-scale models. It was shown that the combined massive and
plate foundations are much more efficient compared to conventional block-type foundations under dynamic machines, such as turbo-
pumps, compressors, fans, centrifuges, etc.
RÉSUMÉ: Il est proposé un nouveau mode de fondation pour des machines supportant des charges dynamiques appellée "la fondation
combinée à blocs et plaques". Elle consiste en un bloc rigide, relié à des plaques de faible épaisseurnoyées dans le sol. Il a été réalisé
des calculs de "fondations combinées à blocs et plaques" pour des machines soumises à des charges périodiques par la méthode des
éléments finis. Les méthodes analytiques du calcul dynamique des "fondations combinées à blocs et plaques" ont été développées
pour des machines subissant des impacts, des machines comportant des organes en mouvement rotatif et des bielles. L’interaction des
"fondations combinées à blocs et plaques" et du sol a été étudiée expérimentalement à l’aide d'essais à grande échelle sur chantier. Les
résultats des calculs analytiques et numériques sont comparés aux résultats des essais de modèles à grande échelle. Il est montré que
des "fondations combinées à blocs et plaques" sont beaucoup plus efficaces que les fondations à blocs traditionnelles pour les
turbopompes, les compresseurs, les ventilateurs, les centrifugeuses.
KEYWORDS: vibrations of foundations, dynamic loading, combined massive and plate foundations, dynamic analysis.
1 INTRODUCTION
Heavy machinery with rotating, reciprocating or impacting
masses requires a foundation that can resist dynamic loadings
and the resulting vibrations. A properly designed foundation is
one that transfers the dynamic load on the soil without high
vibration level. Depending on the types of load or dynamic
equipment various types of foundations are used. A block-type
foundation under machinery is simple and in common used. Its
response depends on the foundation mass and area of
foundation base (Barkan D.D.1962 and Brajama M.D., Bamana
G.V. 2011). A heavy loaded foundation has extremely big
weight and as a result its natural frequency is very low.
Therefore, such foundation under low-frequency loading can
have a very high level of vibration. Furthermore, in case
operation of impact machines, it can be dangerous for building
with low resonance frequency. No changes of dimensions of
such foundations enable geotechnical engineers to decrease
considerably the vibration level.
In the article new forms of foundations under machines with
low dynamic loadings are presented
.
They were named
«Combined massive and plate foundations” (Fig. 1).
Foundations such as these consist of deepened rigid solid mass
and attached to it in soil thin horizontal plates (Kirichek Y.
2011). Its natural frequencies can be sat in a wide frequency
range by changing dimension and location of attached thin
horizontal plates in soil. As a result natural frequency of such
foundation can be significantly higher in amount then of block-
type foundation and vibration level of the combined massive
and plate foundations under low-frequency loading and
impacting machinery generally is considerably lower.
2 LARGE-SCALE FIELD TEST
For studding behavior of the combined massive and plate
foundations under low-frequency loading large-scale field tests
were conducted. The comparison of the footing vibration tests
with theory was done. For these tests, the vertical and horizontal
dynamic forces on footing were generated by rotating mass
vibrators. The large-scale models were 1.5 m in wide and 3.71
m in length (See Fig.2).
a)
b)
Figure 1. Combined massive and plate foundations: a – a solid block
and three plates, b – a solid block and two plates.
Figure 2 shows the large-scale model of massive and plate
foundations with the plate on the top or at the foot.
