Pile Shoes Needed? 7

[smledig]

I’m a recent college graduate and newborn in the field of Structural Engineering who has been assigned to look over some specs that are waiting for construction and I noticed in the notes that they want “pile points” or “shoes” provided on the end of each pile prior to the start of pile driving operations. After researching the subject, I found that these are primarily utilized when driving through hard strata and bedrock. I did notice that in some areas, they are removing pre-existing 14”square conc. piles 5ft. below the G.S. and needling HP 14 x 73 piles in between them. Could this be the primary reason for the “shoes/tips”? Do they think that they could possibly hit or run into the cut and abandoned piles? The project is in South Louisiana and in trying to use my better judgment on this one, but I don’t see why these additional services are needed. I checked over the boring logs and the layers are comparable to other boring logs I’ve seen on similar jobs in the area, and they don’t seem to require these additional task. Can anyone explain to me why he or she is requiring the “tips”? I can’t see a Cyprus stump being the issue and that’s probably the hardest thing that could possible be down there.

 

[civilperson]

I have driven many thousands of piles in south Louisiana without any shoes. If the piles intersect the previous piles, then refusal will occur immediately and a new location must be tried.

 

[msucog]

ask the people that put the notes on the plans and/or the geotech that made the recommendations in the first place.

 

[Drumchaser]

?......could it be that you are mistaking the shoes for the bonnet attached to the driving equipt.?, or cushion blocks, or pile tip elevation.

Have not driven any piles in S. LA., but close to it, and I am with civilperson on this one.

 

[DRC1]

My bet is that they copied the spec from another job with out carefully reading it to see if itwas appropriate.

 

[BigH]

DRC1 has hit the nail on the head . . . I have seen specs where established standards are "improved" - why? Because the British Columbia Municipal Engineers wanted it - but no where else in the world . . . apply a BC requirement to SE Asia . . . The other biggie is specifying a product that comes only in North America whereas the manufacturer supplies the same product in Asia but under a different name . . . too hard to look up what is locally available (name-wise and product-wise).

 

[hollowstemhead]

Often times drive shoes or tips are utilized on end bearing piles to prevent piles from "walking" when being driven. That is, if the bedrock surface is fairly sloped, the pile won't seat well and will skid down the rock slope before getting appropriate set counts. Shoes can help give more bite with less chance of crippling. What type of material are you driving through? If it's an uncontrolled fill, the geotech could have reason to assume there is some debris that could promote pile crippling or tough driving without shoes/tips. The "blanket statement" spec issue could certainly be the case too. Definitely discuss with your geotech, in certain situations shoes can be an affordable insurance policy.

 

[smledig]

Drumchaser, No it clearly says in the notes on the bottom right corner of the pile layout sheet to "Provide piles points or shoes on teh endo of each pile prior to the start of the pile driving operations".
DRC1 & everyone in agreeance, I think that's exactly what's going on. As I completely read the specs they also have comments in the spec that specify to not drive piles when the ground is frozen. Now we all know that certain sub-mantle and core layers of the earth will freeze over about the same time South Lousiana soil freezes solid. I spoke to one of the ITR reviewers at the office and he told me, its a no harm no foul type issue, but I then told him when driving 273 piles that could be quite a cost to tip or shoe each and every pile before driving. Thanks everyone for your comments and input as they were all helpful.

 

[civilperson]

Southern Louisiana has no end bearing piles as such. The hundreds of feet of sands depth require side friction for majority of support and the end bearing is ignored as negligible. Still no shoes required unless a cover plate for pipe pipes fits into that category.