Bearing capacity for Calcarenite rock for mat foundation
Bearing capacity for Calcarenite rock for mat foundation
(OP)
Hello,
I have a geotechnical report that estimates the allowable bearing capacity for isolated footing and raft foundation on a site predominantly composed of Calcarenite sedimentary rock.
The geotechnical engineer estimated the bearing capacity for a raft foundation to be 2600 kPa, which, in my opinion, seems too high. The building is designed to be 8 stories high above ground with 2 stories underground.
I have attached a screenshot of the geotechnical report section addressing this.
I would appreciate any opinions on this matter. I am a structural engineer.
I have a geotechnical report that estimates the allowable bearing capacity for isolated footing and raft foundation on a site predominantly composed of Calcarenite sedimentary rock.
The geotechnical engineer estimated the bearing capacity for a raft foundation to be 2600 kPa, which, in my opinion, seems too high. The building is designed to be 8 stories high above ground with 2 stories underground.
I have attached a screenshot of the geotechnical report section addressing this.
I would appreciate any opinions on this matter. I am a structural engineer.
![](https://res.cloudinary.com/engineering-com/image/upload/v1708196669/tips/Report_cgoeth.png)
RE: Bearing capacity for Calcarenite rock for mat foundation
Is it unusual because you have never seen 2600 kPa allowable bearing capacity for this type of rock in your area? What parameters are usually given? Or have you not worked with this rock before? Are there similar buildings nearby with similar heights and loads?
What are you using the bearing capacity for? Bearing capacity, or are you doing the cheeky structural engineering thing and taking that allowable bearing and converting it into soil springs for slab design?
RE: Bearing capacity for Calcarenite rock for mat foundation
RE: Bearing capacity for Calcarenite rock for mat foundation
RE: Bearing capacity for Calcarenite rock for mat foundation
RE: Bearing capacity for Calcarenite rock for mat foundation
“cheeky structural engineering thing and taking that allowable bearing and converting it into soil springs for slab design l This is what I wanted to do, I asked the geotechnical engineer for a better estimate with a plate test and his response was to use that correlation\equation!!)
RE: Bearing capacity for Calcarenite rock for mat foundation
RE: Bearing capacity for Calcarenite rock for mat foundation
Also you approach is flawed, work out what settlement you have and then work out a spring stiffness. Even that approach is somewhat flawed but more accurate than yours i think