drilled displacement piles

huangyhg

drilled displacement piles
anyone out there very familiar with these types of piles?
whats the maximum capacity of a typical pile?  how large a diameter pile is typical?  i've got a situation where original piles were 50 ton, and i need 70 ton.  no piles installed yet, but i'm hoping i can increase the diameter of the pile to get the 70 tons.
one brand is the "dewaal" pile system. i used them for an electric utility cooling tower about 6 years ago. diameters of 12" to 18" and allowable loads up to 250 tons/each are common. they were very cost effective and have performed well. here is a link
allowable loads to 250 tons....sounds like a capacity of the pile but what about the soil and rock (if there)....
and if the allowable load is controlled by the soil or rock then how can they claim 250 tons?
regards,
qshake
eng-tips forums:real solutions for real problems really quick.
qshake - the 250 ton capacity is taken directly from the referenced link (see line 19 of the text).
on cooling tower job  mentioned, (based on geotechnical recommendations) i had specified point bearing, steel hp 12x53 with nominal 40 ton capacity. the contractor bid the traditionally driven hp, and offered an unsolicited proposal for a one-for-one replacement of the hp with dewaal piles. since this contractor was the low bidder on the specified hp approach, we pursued the unsolicited proposal and negotiated a turn-key design for the dewaal pile (at a substanial savings). here is a link to the engineering firm that did the design for that job