Residual properties of Timber Pile

[pau01ste]

All,
I am attempting to reassess a dockwall at a wharf. The soft soil behind the wall is improved by the use of timber piles. A timber frame (a sort of pile cap) connects the piles. The frame is located about 10 m below grade level and is overlain by fill. The wall and piles were constructed about 70 years ago.
Ideas on how to estimate the residual properties of the timber piles please.
Also references about estimating the contribution of the piles to slope stability, under seismic excitation, needed.

Thanks

 

[sfamularo]

How do the timber piles improve the soft soil behind the bulkhead? I'm not sure I understand...are they in front of the wall or inshore of it?

What do you mean residual properties of the timber piles? Remaining allowable stress due to time? In all likelihood, the piles residual properties are based upon their current condition - the amount of deterioration from rot and marine borers, salt/fresh environment, and exposure to harsh weather or mechancial deterioration.

I don't have any references on how the piles affect the slope stability. I know they have a keying effect in the slip/failure circle as I have seen references before. If I find anything I'll add to this post.

Please provide more details so I can clarify my response.

Regards,

Steve

 

[pau01ste]

The piles are inshore of the wall. They are used to stabilise the weak soil behind (onshore) of the wall. What I an interested in is estimating the effects of ageing on both stiffness/strength and sectional properties of of the piles. For example, if initial sectional area/rigidity of the piles were A/Z, and their stiffness/strength, Eo/Y, I would like to find souces for estimating the corresponding values to use for reanalysis of the constibution of the piles to slope stability, 70 years after construction.
Thank you for your interest.

 

[sfamularo]

Here are some references I found online:

http://www.steel.citg.tudelft.nl/research/cost-c5-zurich.pdf

http://www.steel.citg.tudelft.nl/research/lifetimemodelling.pdf

Hope these help.

Typically, in old timber waterfont structural analysis, we use the existing design values and use the deterioration of the wood (loss of section, amount of decay infestation, softness of pile, etc.) as a guide for reduced area and section modulus.

If you are just trying to determine the effect of the piles on the possible slip failure circle, the above is easily justified. However, if you are doing a more in-depth structural analysis of a timber structure, you may want to reduce the stiffness and strength by some factor, or using some of the references in the above papers.

Hope this helps...

Steve

 

[pau01ste]

Steve,
Thank you.
The papers look relevant.
Ade