×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Bearing Capacity Calculation

Bearing Capacity Calculation

Bearing Capacity Calculation

(OP)
Dear All:

I am wondering how to consider the effect of soft soils (Soils with low 'N' values)in the boring while calculating the bearing capacity using General Bearing Capacity equation. I mean the soft/weak soils are not at footing depth but are present at a depth between 25-40 ft along the profile and the N values spiked later. How do account or reduce bearing capacity for this type of situation.


Thanks
NT

RE: Bearing Capacity Calculation

The Navy Manual, DM-7.2, addresses bearing capacity of two-layer foundations on Pages 137 and 145. You can download the manual for free.

Generally, I would rough-size the footing based on the strength of the upper layer, then compare the thickness of the upper layer to the width of the footing. If the depth to the soft layer is more than twice the footing width, it may have no effect, but check it using Page 145.

You will need to address settlement separately. Remember that a point in the deep layer may be stressed by more than one footing.

RE: Bearing Capacity Calculation

(OP)
Aeoliantexan:

Thanks for the reference.

NT

RE: Bearing Capacity Calculation

if you are using N-values to correlate strength, take the weighted N-value to a depth of 2B (4B for strip footings) and use that average value to derive bearing pressure. It'll likely be o.k. On the other hand, you need to look at elastic solutions to determine the stress increase in the layer to determine how much settlement will result from the loads acting on this layer. You may (will likely) need to adjust the foundation bearing stress to limit settlement from this layer. It'll not likely be designed based on ultimate bearing pressure, but on the basis of foundation performance (i.e., settlement).

f-d

¡papá gordo ain’t no madre flaca!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources