Settlement Calculations 1

[nagatalluri]

Guys

Can you please suggest me a good software (possibly a free one) for consolidation settlement estimate. Evaluation versions are also fine as I am going to use the software one time for a report.

Thanks for your input
NT

 

[oldestguy]

Sounds like a lot of fooling around when a hand calculation will probably take no more than 10 minutes. There are better ways to impress a client.

 

[nagatalluri]

Sir

Thanks for your input. I was asked to prepare a report on settlement calculations. I have done the hand calculations and demonstrated that the settlement is beyond the acceptable limit but now I am trying to show it in a report using a software program.

Please let me know if you have any recommendations

Thanks
NT

 

[tsek]

I know that consolidation settlement can be calculated in Plaxis. However, if you don't provide the proper input values, you will get bullshit results. Why not just use Excel? I agree with oldestguy on it not being worth it.

 

[tsek]

FHWA also currently recommends the FoSSA program by ADAMA Engineering. I've never used it.

 

[oldestguy]

On how to show in a report the calculation results, well that depends on who is getting it. In my experience they don't give a darn as to how you got your answer, since that is your expertise. In general the simpler you can make your report, the better it is accepted usually. Most of the time I understand that my clients skip through all the garbelldy gook in front and look for the recommendations. If they see a computer program was used, unless they are well familiar with it and know its failings, they trust you to know that it produces dependable results and that's all. As I see it, when computer programs are referenced, the intent of the report then mentions that because it enabled the report writer to do a great many useful calcs and save time, thus money. For a simple settlement calc, that is not usually the case.

 

[nagatalluri]

Sir

Thanks for your input. It is indeed much helpful

NT

 

[nagatalluri]

Guys

One final question. While calculating the consolidation settlement, we check the overburden pressure at center of clay layer, pre-consolidation pressure (Pc) and stress increase at center of clay layer and use either Cc or Cr.

In case if the pre-consolidation pressure is in between the overburden pressure and sum of overburden pressure and Pc, some text books are referring to a method involving two step process

Step 1. overburden pressure to Pc using Cr
Step 2. Pc to sum of (overburden + stress increase) using Cc

some of the references do not consider this approach and the calculation is based on using one Cc as the Pc < (overburden + stress increase)

Can you guys comment which method is more conservative and practical?

Thanks for your input

NT

 

[tsek]

You have to make sure that the clay is already in its final stages of primary consolidation due to the pre-consolidation pressure. If you're not sure, then the latter is more conservative to use.

 

[nagatalluri]

tsek

Thanks for the response. How do we determine that clay is in its final stages of primary consolidation ?

NT

 

[oldestguy]

Of the many, many calculations to predict settlement, only one turned out to be reasonably accurate as to timing and amount. Most of the rest turned out to show less settlement than predicted and usually more rapidly than predicted. The major "problem" in my view is knowing exactly the location of drainage layers. Thus, in a fussy case, I depend on either test fills or control of the work based on settlement platform data. Specifically in answer to the question, never used a combination of values, since the test data probably was never that good..