Investigation of effectiveness of preloading method for existing foundation underpinning by centrifuge tests
A conceptual preloading method was proposed for reducing loads carried by exiting piles by means of transferring partial loads on existing piles to underpinning piles. For investigation of the effectiveness of preloading method, a model preloading apparatus used for centrifuge tests was developed and a series of tests was performed on an underpinned foundation. In the centrifuge test, a pre-load was firstly applied to the underpinning pile to verify the load transfer effect of the preloading apparatus. Then additional loads were applied to the foundation to evaluate the load sharing behaviour of existing and underpinning piles. The feasibility of the preloading apparatus based on the preloading concept was verified through the experimental results. Moreover, under additional loading, the preloading value affected the load sharing capacity of existing and underpinning piles. Therefore, in the design of underpinning considering preloading, a proper pre-load range which is less than both linear pull-out behaviours of existing foundations and linear compressive behaviour of underpinning piles was suggested.
Keywordspile foundation underpinning preloading method centrifuge test vertical extension
This research was funded by (19RERP-B099826-05) from Residential Environment Research Program (RERP) funded by Ministry of Land, Infrastructure and Transport of Korean government.
- Armour, T., Groneck, P., Keeley, J., and Sharma, S. (2000). Micropile Desgin and Construction Guidelines-Implementation Manual. FHWA-SA-97-070, Federal Highway Administration, Washington, DC.Google Scholar
- Bruce, D. (1988). Aspects of minipiling practice in the United States. J. Ground Eng. 21, No. 8, pp. 20-33.Google Scholar
- EN, B.S. (2004). Eurocode 7: Geotechnical Design-Part 1: General Rules. British Standards: London, UK.Google Scholar
- Kulhaway, F.H., Kozera, D.W. and Withiam, J.L. (1979). Uplift testing of model drilled shafts in sand. Journal of Geotechnical and Geoenvironmental Engineering, 105. ASCE1403 ProceedingGoogle Scholar
- Kulhaway, F.H. (1985). Drained uplift capacity of drilled shafts. In Proceedings, 11th International Conference on Soil Mechanics and Foundation Engineering, pp. 1549-1552.Google Scholar
- Lizzi, F. (1980). The use of root pattern piles in the underpinning of monuments and old buildings and in the consolidation of historic centres. J.L’Industria Costruzioni, 110, 25.Google Scholar
- MOLIT (2013). Housing Act, Korea Ministry of Land, Infrastructure and Transport, pp.2.Google Scholar
- Mayerhof, G.G. (1976). Bearing Capacity and Settlement of Pile Foundations. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 102, pp. 195-228.Google Scholar
- Terzaghi, F.T. and Peck, R.B. (1967). Soil Mechanics in Engineering Practice. 2rd ed. John Wiley and Sons, New York.Google Scholar
- Wang, C.C., Han, J.T., Jang, Y.E., Ha, I.S. and Kim, S.J. (2018). Study on the Effectiveness of Preloading Method on Reinforcement of the Pile-Foundation by 3D FEM Analysis. Journal of the Korean Geotechnical Society, Vol. 34, No. 1, pp. 47-57.Google Scholar
- Wood, D.M. (2004). Geotechnical Modelling. 1st ed. CRC Pres, Boca Raton, FL.Google Scholar