×
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.

# LPile, Weak Rock and compressive strength

## LPile, Weak Rock and compressive strength

(OP)
I am designing a drilled shaft to bear in a soil layer the geotech recommends modeling in Lpile as "weak rock".

The allowable end bearing pressure given for this layer is 14ksf (= 97 psi) and for input in Lpile the compressive strength= 50 psi, RQD 20% and k rm value = 0.0007.

I run LPile and there are a few warnings:

1. "The input value for k_rm used by the weak rock criteria is greater than 0.0005. This value is outside the recommended range of 0.00005 to 0.005. You should check your input data for accuracy."

Not sure the reason for this warning. Even though 0.0007 is higher than 0.0005, it is still within the recommended range.

2. "An unreasonable input value for compressive strength has been specified for a soil using the weak rock criteria. The input value is less than 100 psi. You should check your input data for correctness"

Is there a specific compressive strength range for this soil layer? some literature available? should there be a correlation between the allowable end bearing pressure given for axial load design with the compressive strength value for input in LPile?

### RE: LPile, Weak Rock and compressive strength

50psi is too low to be rock. BS5930 defines rock as a UCS above 0.6MPa, which is around 90psi so close to 100psi. Not sure what ASTM says.

Why has your geotech recommended modelling it as weak rock! The soil models available should be appropriate

### RE: LPile, Weak Rock and compressive strength

I would notify your geotechnical engineer that their parameters are setting off alarms in LPile. It could be that they don't use the software so they're just throwing conservative numbers at you and guessing which p-y curve model to use.

What type of rock are you dealing with?

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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!