Deep foundation Recomendation

[deemtocomply]

I'm currently designing foundations for a three-storey apartment building located near the coast. The geotechnical report indicates sandy soil conditions with a high water table (approximately 1.5 meters below ground level). I'm considering the use of concrete piles, but I’m unsure whether this is still a suitable option under these conditions.


If concrete piles are viable, what additional factors should I take into account? One concern is the potential for reinforcement corrosion due to the aggressive environment. To mitigate this, I'm planning to increase the concrete cover and possibly control the crack widths in the piles. Would these measures be sufficient, or should I consider an alternative foundation system?

 

[HTURKAK]

I'm considering the use of concrete piles, but I’m unsure whether this is still a suitable option under these conditions.

IMO, suitable but if precast driven pile since the compactness and quality control better than bored piles.
You may consider steel driven piles with choosing thickness with suitable corrosion allowance together with corrosion coating and CP .

 

[jhnblgr]

What does the geotechnical report say and what were the characteristics and depth of the borings?

Did you get any at grade bearing capacity?

Research galvanized or epoxy coatings, also maybe call up a supplier to see what they typically run into.

 

[phamENG]

Lean on the geotech for pile recommendations. They'll know if you need them for bearing/settlement considerations, and they should know if you need them for scour if you're that close to the coast - but you may need to nudge them in that direction if there's a regulatory reason that goes beyond site specific engineering.

 

[deemtocomply]

Thanks, everyone. That was very helpful.

I've just reached out to the geotechnical engineer for recommendations. Based on the borelogs, the bearing capacity is quite low: around 200–250 kPa end bearing at a depth of 3.5 meters, with no data available beyond that.

Would it be appropriate to design the piles as marine piles, such as steel tubes filled with concrete? Or would that be overengineered for a project of this scale?

 

[deemtocomply]

IMO, suitable but if precast driven pile since the compactness and quality control better than bored piles.
You may consider steel driven piles with choosing thickness with suitable corrosion allowance together with corrosion coating and CP .

The corrosion allowance applies to steel piles, but what about the reinforcement in bored or driven concrete piles? I can increase the concrete cover, but controlling crack widths could be challenging, especially since I need to account for moments caused by lateral loads.

 

[HTURKAK]

he corrosion allowance applies to steel piles, but what about the reinforcement in bored or driven concrete piles?

I suggested two options ,
- Precast driven pile , ( size could be 300X300 mm)
- Steel pile with protective coating and increased wall thickness with added CA. ( size could be Pipe DN 300)

I did not suggest bored piles however , if this is the only alternative , you may consider epoxy coated reinf.

 

[LittleWheels]

We ban epoxy-coated rebar on our designs. Too much opportunity for corrosion initiating at coating defects or coating damage, which is then localised and intense. Most of our work is marine or coastal.