×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# Soil Surcharge at Abutment Case 2

## Soil Surcharge at Abutment Case 2

(OP)
I can't find an example anywhere depicting case 2. All of the tables in the manual show simplified calculations for case 1. I understand how to calculate case 1 entirely but I am having issues visualizing how to compute the lateral pressures due to case 2 in regards to surcharge only.

Any insight or reference would be extremely helpful.

### RE: Soil Surcharge at Abutment Case 2

Case 2 is just an area surcharge load of P = q x Ka. The lateral pressure diagram would be rectangular. You may need to read AREMA to see how it recommends applying a perpendicular E80 surcharge. The load would probably be applied to a length of wall that is greater than 9' (the tie length).

### RE: Soil Surcharge at Abutment Case 2

(OP)
I have gone through and read AREMA but would it only gives a paragraph. Would it still be the "q" calculation shown in the first part of the calc sheet? (the 80,000/(9x5) to get the rectangular distribution for a 1' strip?)

### RE: Soil Surcharge at Abutment Case 2

Yes. q = 80,000# / (5' X 9'). If you can't find anything in AREMA about how wide to spread this perpendicular strip load surcharge, you may need to pick some reasonable width that is greater than 9 feet. Or, talk to the railroad's engineer.

### RE: Soil Surcharge at Abutment Case 2

(OP)
Ok I figured out how to distribute it through ballast over a different area. I know in AASHTO when you're applying surcharge, there's a certain depth where it stops having an effect laterally on a wall; would that be applicable to a scenario like this or do I have to extend the rectangular distribution an infinite length depending on my configuration?

### RE: Soil Surcharge at Abutment Case 2

Many times over the past years, I have spread RR loading out over the ballast. For example, for 9' long ties with 3' of ballast below, maybe you will be allowed to spread the load over 9' + 3' + 3' = 15'. Also, the load could be applied at the bottom of the ballast rather than near the ground surface. However, sometimes this is not allowed. You really should check the specific requirements of the particular RR you are dealing with.

### RE: Soil Surcharge at Abutment Case 2

(OP)
Thanks PEinc. I was able to find a supplemental publication to AREMA that explained in perpendicular situations it spreads over the width of the tie and depending on your ballast like you suggested BUT only up to a max of 14ft; I don't think any further reduction is allowed beyond this point. The last thing I need to figure out is if I have an abutment sitting on a drilled shaft wall, how far down I would have to run this rectangular distribution of a load.

### RE: Soil Surcharge at Abutment Case 2

If the drilled shafts are tangent to each other, they behave like a sheet pile wall and the surcharge would extent to the full depth of the shafts. If the shafts are spaced apart, you probably will be required to apply the surcharge to the full width and length of the shaft, at least to the top of bedrock, if any.

### RE: Soil Surcharge at Abutment Case 2

(OP)
I was hoping that wouldn't be the case but it seems like that's what it's going to end up being. Thanks for helping me out.

#### 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.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!