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!

*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.

Jobs

Shear strength testing

Shear strength testing

(OP)
Hello

We are requried to caclulate the bearing capacity of the soil under a proprsed weigh in motion railyard scale. the scale has a slab foundation (rectangular) that is to be placed approx. 5 feet deep below ground surface. the soil is fine grained (Clay and silt). To calcualte the bearing capacity, we need to estinate the shear strength of the soil for use with the bearing cpacity equations.

i am trying to figue out which Triaxial test (UU) or (CU) to run on the samples to obtain shear stregnth for bearing capacity calcuation. I am not sure where the groundwater or in other words is the smaple saturated at 5 feet deep. I was comptempalting a UU test to get a shear stregnth for the short term loadng conditions that is going to govern in this application. However if the sample is not saturated then the UU could give pretty high shear strengths. Any suggestions would be very helpful

thanks

RE: Shear strength testing

I'd be much more concerned with differential settlement than soil shear strength, which likely has no use there.

RE: Shear strength testing

Agree with oldestguy - this is more in line with serviceability issues than shear issues since the weighing scales probably, if they are like ones I've dealt with in the past, very sensitive to settlement - in fact on one job they said "no settlement". Further, the fact that you are removing 5 ft of soil - and the pit is likely to behave as a bathtub - you therefore can counterbalance your loads to the removed soil and bearing shear would be of little concern.

You do need to characterize the soil - carry out a proper investigation which you seem not to have done as yet since you have indicated you do not know where the groundwater is - and not much as far as classification of the soil. You can always do in situ shear vane tests to determine the shearing strength - but you need to have more information as to compression behaviour of the soil. Consolidation testing - you also need, because you are digging a pit need to know how much rebound you will get. You can also do a CIU test with pwp measurements.

RE: Shear strength testing

There also is the potential for overall "rocking" as the load comes on or goes off. With rail connections at each end of the "box", I would think the width and overall length of the supporting slab under the "box" may have to be sized for a limiting deflection at the junction with nearby ground supported rails. Perhaps handle this with an approach slab under the rails, as is done at highway bridges. I've noticed that under most rail traffic a noticeable deflecti0pn of the rails occurs as the loads go by.

I have not done tests to measure elastic action, etc. so perhaps some member here can elaborate.

I once had the job of evaluating a distorted (during placement) corrugated metal culvert pedestrian walkway under a railroad. I measured deflection of the "roof" as well as side to side "squashing" effect. With the locomotive and its distributed loadings not much effect. But cars loaded with iron ore really created deflections, but left no permanent distortion.

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


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:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close