Timber Pile - reinforce with concrete block underwater

[jgeng]

I have an existing structure supported over approx. 10ft of water by timber piles. I need to increase bearing capacity, uplift, and add fixity to the pile for lateral resistance. I was thinking of having a concrete block placed at the mudline of the pile underwater. The block would be secured to the pile by dowels drilled through the pile. Looking for opinions on constructibility and how costly this fix would be? or alternative ideas for increasing strength? perhaps a timber grade beam bolted to the existing piles at the mudline underwater?

 

[NS4U]

can you just drive new battered piles? what about drilling micropile? solves all three problems.

I am not sure adding a concrete blob will give you the fixity you are looking for and moreover it will likely be a significant amount of added dead load which I think will be difficult to transfer by dowels.

 

[beaming]

I suppose the piles are treated. The holes would take the benefit away.
To know whether the concrete enlargement would do any good, you would have to know a lot about the soil, or put a whole lot of concrete, which, if engaged with the pile, as by bolts, might load the pile to misfortune.
Micropiles sound better to me.