TENSION TESTS ON BORED PILES IN SAND
Piling foundations are normally used in conditions, where the distance from the ground level to the firm layers able of carrying the actual load is more than three to four metres, and very often the choice is between driven piles usually made from reinforced concrete and bored concrete piles cast in situ. In terms of economy bored piles seem to be advantageous over driven piles at smaller depths, around 4 – 6 m, whereas driven piles are usually preferred at greater depths. The equipment used for driven piles is much heavier than the equivalent used for bored piles which - due to transportation costs - makes the latter more attractive, where only a smaller number of piles are to be installed. In urban areas there is always a risk of the driving of piles to cause damage to neighbouring buildings, and also in such circumstances bored piles may be preferable. Naturally a crucial factor when deciding the type of piles to be used at an actual project, must be the load bearing capacities, which can be attributed to the two types of piles.
The present investigation of the bearing capacity of piles is limited to dealing with the uplift capacity of bored piles in sand, as this seems to be an area of disagreement among the codes of practice of various countries. In order to examine this issue ten bored piles of lengths varying from 2 - 6 m all of a diameter of 140 mm have been tested, and furthermore the capacities according to The Danish code of practice – DS 415, The German code of Practice – DIN 4014 and British/American practice have been calculated.
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