onsiteeng
Structural
- Sep 2, 2009
- 14
Hi All,
On a recent marine piling project the depth from the water surface to the mudline was around 40ft. They used a ICE 28B vibratory hammer to set the open pipe piles(100T design load capacity). The hammer plus the 110ft 24" Diameter 1/2" thick pile sank 15ft through sand/silt under its own weight to limestone bedrock. The piles were then driven a further 50ft to refusal. It is assumed the pile refused in the igneous bedrock which underlies the limestone. The piles were then dynamically tested with a PILECO D19-42 open ended diesel hammer. The results are in the attachment. I have the following questions.
1) Given that the pile lengths, depth of water and assuming similar geotechnical conditions(piles were all tested in a 50ft x 50ft area) why is there such a range of capacaties(185kips to 960kips)
2)Is it possible some of the pile tips have started crushing increasing the bearing area at the tip. Would this cause an increase or decrease in tip capacity? I was thinking it may increase it.
3) Assuming the pile is not damaged can you take the pile capacity and work backward through the flexural buckling equation to determine effective pile length and therefore point of fixity in the sea bed.
Thanks
On a recent marine piling project the depth from the water surface to the mudline was around 40ft. They used a ICE 28B vibratory hammer to set the open pipe piles(100T design load capacity). The hammer plus the 110ft 24" Diameter 1/2" thick pile sank 15ft through sand/silt under its own weight to limestone bedrock. The piles were then driven a further 50ft to refusal. It is assumed the pile refused in the igneous bedrock which underlies the limestone. The piles were then dynamically tested with a PILECO D19-42 open ended diesel hammer. The results are in the attachment. I have the following questions.
1) Given that the pile lengths, depth of water and assuming similar geotechnical conditions(piles were all tested in a 50ft x 50ft area) why is there such a range of capacaties(185kips to 960kips)
2)Is it possible some of the pile tips have started crushing increasing the bearing area at the tip. Would this cause an increase or decrease in tip capacity? I was thinking it may increase it.
3) Assuming the pile is not damaged can you take the pile capacity and work backward through the flexural buckling equation to determine effective pile length and therefore point of fixity in the sea bed.
Thanks