An Experimental Study on Uplift Capacity of Short Piles with Shear Keys Studies on the windproof charactemstics of a greenhouse (IV)

• Published in: Transactions of The Japanese Society of Irrigation, Drainage and Reclamation Engineering Vol. 1990; no. 147; pp. 61 - 67,a2
• Main Authors: SHINO, Kazuo, NAKAZAKI, Akito
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society of Irrigation, Drainage and Rural Engineering 25.06.1990
• Subjects: Shear key
• ISSN: 0387-2335; 1884-7234
• DOI: 10.11408/jsidre1965.1990.147_61

Vinyl covering greenhouses are very lightweight structures and is often pulled out due to the wind. Therefore, improvement in the windproof capability of greenhouses is an important problem. Particularly, uplift capacity of the pile foundations is one of most important subjects regarding the windproofing of greenhouses. Normally, footing foundations are not used due to economic and construction considerations with cylindrical concrete piles generally being used. Therefore, two types of cylindrical concrete model piles with shear keys on the surfaces have been proposed for the purpose of increasing ultimate uplift capacity. The shape of a shear key is semi-spherical and its diameter is 15 mm. Pile diameter is 7.5cm and L/D are 2.6-5.3. Pull-out tests were carried out using sand have two densities loose and dense. Uplift capacities of piles with shear key are compared with uplift capacity of piles with no keys. Results obtained are as follows: The rate of increase in ultimate uplift capacity become larger due to the increase in the pile length of the embeddment. In the case of loose sand, an increase in ultimate uplift capacity is slightly smaller for both piles, but in the case of dense sand, an increase of about 30-50% in ultimate uplift capacity in the case of a pile with a key. The pile movement at the time in which the pile is pulled out occurs in proportion to the pile length of embeddment in both piles.