Caisson Concrete Guide Collar Design

[NeilQ]

We have been tasked with assisting a contractor with the design of a concrete guide collar for a 12.5m diameter concrete caisson.

The caisson is proposed to be jacked with an arrangement of 8 jacks spaced equidistantly around the perimeter. The maximum jacking force is 400kN. We have a maximum achievable width of the guide collar of 1.2m due to temporary sheetpiling to the perimeter.

We are considering the following mechanisms:
[li]Uplift[/li]
[li]Overturning about the bottom outside corner of guide collar[/li]

The uplift and overturning will both be resisted by the self weight of the collar. We have taken the lever arm acting at the centroid of the annulus segment.

Would this be the correct way of assessing this type of element?

Thanks

Neil

 

[BUGGAR]

I would agree but I would be cautious of soil inconsistencies. I've experienced tunnel shields that get hung up on a veins of hard soil or boulders and the day goes dismal. Is geotech good? If the sheetpile drove OK it sounds good!