What do I get from cyclic loading for pile compression test ?

[Tatsu]

I am looking at ASTM D1143-81 "Standard Test Method for Piles Under Static Axial Compressive Load". Section 5.2 Cyclic Loading (Optional) explaines how to apply 3 steps cyclic loading.

I am wondering what extra interpretation I can make from cyclic loading test compared to simple loading. Does it make tell-tale data more useful to separate shaft resistance and toe resistance ?

Any comment/reference book/paper will be appreciated.

 

[GeoPaveTraffic]

No, cyclic loading is not going to improve the interpertation of tell-tale data. Cyclic loading is just going to allow you or the design engineer to better determine how the pile will behave under cyclic loading conditions.

If your pile will not be subject to significant cyclic loading, there is no reason to perform a cyclic load test. The ASTM has many loading methods, most of which are not applicable for most piles. If your will mainly be subjected to static compression loads, I would either use the quick loading or slow loading depending on the soil type that the pile is getting its capacity from. If the pile is in sand, quick load; if in clay, slow load.

 

[BigH]

Gives you a better handle on what is "elastic" shortening of the pile vs the plastic or load caused settlement of the soil.

 

[Tatsu]

GeoPaveTraffic and BigH,

Thank you for your comments. Have you ever seen any schematic/paper showing interpretation of pile top settlement, tell-tale and difference of them under "cyclic loading" ?? ... some schematic explaining pile behaviour under cyclic loading based on tell-tale and pile top settlment.

 

[BigH]

I'll have to look them up after I get back from Bali.

 

[GeoPaveTraffic]

Don't recall ever seening a good write up.

But it isn't that complicated. Just plot movement versus load for each of the points where you have movement. On the same plot add the theoretical movement due to elastic strain. Compare the curves and interpret how much acutal movement of the pile you are seeing. Realize that when you unload a pile that has been loaded, that some amount of residual load is present in the middle to lower portions of the pile.

 

[august1974]

Generally, fill should be treated as suspect material except if the engineering properties of the borrowed pit material is comfirmed through adequate laboratory tests.also, the geological conditions of the area to be filled such as the subsoil underlying the fill needs to be certain . for instance, if the fill is placed over a highly compressible alluvium deposit of about 6.00m thick, there is large tendency for the placed fill to undergo some form of excessive settlement under its own weight in addition to compression of the underlying soil.

Therefore, fill should be treated specially.

Remains.
Fola adeniyi @ Groundmast Associates.Lagos.