Pile not Set (4 full lengths about 24 m) at ex-mining area

[alexgan]

Currently I am doing the construction for the Double Storey Link House at Malaysia.

However, during the piling, a lot of piles is not set after reaching 24 m.

The factor of Safety that the engineer used is 2.2. The most of the usage of the pile is only up to 70%.

I would like to ask, do you think the friction of the pile will be able to carry the load?

Please kindly advice.

 

[PEinc]

You did not give enough information for anyone to answer your question accurately. My advice is to ask the engineer who designed the piles.

 

[csd72]

Are they meant to hit rock?

If this is the case then you need all of them to go to rock or there will be differential settlement. Even if it is not to rock there will be some differential.

2.2 is a typical factor of safety and is necessary to to a large variance between calculated and actual capacities. Do not think of this as 'spare' capacity because it is not.

I do not understand your statement regarding the 70%.

Looks to me like you have 2 options:

1. keep driving these piles until you get the required capacity.
2. abandon these piles and replace with 1 pile each side that will hopefully reach the bearing material sooner.

 

[BigH]

First off, we do not know the nature of the piles being driven or the materials he is driving through. If they are non-displacement piles (say H-piles), and the material they are driving through is loose to compact sands, they may drive "forever" - see Chellis' tome on Piles - he discusses this and offers a few solutions (viz., putting some plates between the flanges about 1/3 up the pile - to give some bearing). I know of one very experienced structural engineer who ended up driving and driving and driving. This happened on a job I was peripherally involved as well. Basically, the designer ended up going with the "set" or capacity based on the geotechnical capacity analysis. In the design of piles, you use this - and try to use "set" to feel safe.

 

[Geoquery]

I worked in Malaysia for the Shah Alam Expressway Project. We used concrete spun piles; each pile section was 12 meter length. We even drove piles to 48 meters. The soil was there peat to a great depth. In fact piles even 24 meter pentrates with self weight. My advise is that drive the pile until the required set is achived. Because the top portion of the pile does not get any friction resistance. And if there is a fill at site, you need to consider the downdrag. Consult the designer for the required set.

 

[VAD]

The answer to your question is yes