Bearing Capacity of Bedrock 1

[Structures33]

If we could put a number on the bearing capacity of bedrock, what would it be? i.e. what is the lowest number that could be used (conservative)? I need to make a strength comparison.
Thanks in advance

 

[DRC1]

Depends on the Rock. Many local codes have presumptive capacities for bedrock. I think AASHTO bridge design manual has them also.

 

[civilperson]

Rock, 1500 to 11,000 psi.

 

[hokie66]

Maybe not "bedrock", but bearing capacity of rock in piles normally starts around 1 MPa, or say 150 psi. This is highly weathered rock, and as civilperson says, fresh rock can be very strong.

 

[fattdad]

Unconfined compressive strength for intact rock can vary from 21.5 psi (siltstone) to 51,500 psi for bassalt. Just using the rational method that would suggest an ultimate bearing capacity of 60 to 144,200 psi (big range). This would equate to 4.3 to 72 tsf with an allowable bearing presure of about 1-1/2 to 24 tsf.

Here's where the body is buried: These values are based on laboratory testing of INTACT rock samples. The presence of joints, the condition of the joints, the orientation of joints, the presence of ground water and natural structural layering(s) can have a dramatic affect.

In summary: You have to define "bedrock", you have to characterize the "bedrock" and you have to do a field study to understand the nature of the defects. Then you can work up the bearing pressure. Here's where "oriented core" can become relavent. . . .

f-d

¡papá gordo ain’t no madre flaca!

 

[soiledup]

Try looking for references to MJ Tomlinson. Good stuff there, promise. Also Waltham's book 'Foundations of Engineering Geology', it's a bit lighter / easier going, almost like an engineering book for pure geologists!! Good stuff there also.