Sensitivity Analyses

by Nate Hekman on June 15, 2009

A GeoStudio user commented on an earlier post (“solving in batch mode”) asking how to generate thousands of similar analyses that differ only by some input parameters.

Interesting question, and I’d like to hear more about what it is he’s trying to accomplish.  But in the meantime here are some thoughts.

Sensitivity

In SLOPE/W, take a look at the Sensitivity analysis (KeyIn Analyses – FOS Distribution – Sensitivity).

Selecting the Sensitivity analysis option.

That will let you specify a range of values for certain properties (such as C, Phi and Unit Weight in the material properties), and will re-run the analysis many times.

Specify a range of values for a parameter.

In Contour you can then do things such as graphing how the FOS is affected by varying Phi. (In the menu that’s Draw – Sensitivity.)

Graphing factor of safety relative to changing parameter values.

Probability

Similarly you can do a Probabilistic analysis in SLOPE/W, where Solve takes care of varying the parameters in a random way using a distribution function you define. It then gives you a probability of failure instead of a factor of safety.

One of the probability graphs.

You can find an example of sensitivity and probabilistic stability analyses on the geo-slope.com web site.

Add-Ins

The other products (Seep, Sigma, etc) do not have sensitivity analyses built in.  (It’s a feature we’re considering adding, so email or leave a comment to cast your vote if you would use it.)

I could imagine doing something similar using an Add-In and a batch file. The batch file could make many copies of the file, giving each a unique name (“dam-1.gsz”, “dam-2.gsz”, etc), then solving each. An Add-In function would be used to specify the property you want to vary. The Add-In would look at the file name (the “1” or “2” part of it) to return a different value for each run.

Not a particularly elegant solution, but it would do the trick. Of course you’d end up with hundreds of files and no simple way to compare results or graph results across the varying parameter as you can do in Slope.

Add-Ins are beyond the scope of what I can go into today, but I have been wanting to delve into them on the blog at some point. Let me know if that would interest you.

XML

An even more adventurous route would be to edit the xml inside a gsz file.  (I mentioned in passing in a few other posts that a .gsz is just a zip file that contains a bunch of other files–one of the xml files it contains is what actually defines all the data in your model.)  The advantage would be you could avoid having thousands of files and instead have just a few files each containing a number of analyses.  That lets you share data (so that moving a point in one file wouldn’t have to be duplicated to all the others), and you may also be able to take advantage of the fact that GeoStudio can graph across analyses.

But editing the xml is not something we officially support, so you’re on your own if you choose that route.

I’m curious what it is you’re doing with your thousands of files. Can you share some more detail? Do the tips I mentioned help? We’re working full-force on the next version of GeoStudio at the moment, so this is a great time to hear about features that would be important to you.

{ 1 trackback }

Short sale
07.23.11 at 6:31 am

{ 37 comments… read them below or add one }

1

Mike 07.15.09 at 2:13 pm

Great blog.

As for similar analyses, sensitivity, etc: I often use SLOPE/W to bound a problem by varying parameters such as the face angle of an embankment, the lateral or vertical extents of some modeled ground improvement zone, the location of a surcharge, etc. The Sensitivity feature is great (use it all the time) but it doesn’t help with varying these types of parameters. If I could do something like vary modeled ground treatment depths in 5 ft increments automatically, that would be awesome! Certainly not thousands of runs, but enough to be time-consuming to do manually.

2

Nate 07.15.09 at 2:16 pm

That’s a great suggestion, Mike. I’ll make sure it’s on our feature wish list for a future version.

3

Giang 09.16.09 at 10:54 am

Dear mr.Grokking,

Could you please show us the format, structure of XML file so that we can write C# to generate the XML file.

Thank you

Giang

4

Nate 09.16.09 at 10:58 am

Sure, I’d be happy to write something up about the xml format we use. Thanks for the idea.

5

Giang 09.21.09 at 9:54 am

Dear Nate,

Please write something about the xml format file. I am doing now a module to generate the XML file which will be enable me to run Slope/w many time for optimization analysis. Therefore, I need your format.

Many thanks

6

Nate 09.25.09 at 12:00 pm

I will try to get to that soon, Giang.

7

Erica 02.01.10 at 8:14 pm

HI,
A sensitivity analysis option within SEEP would most definitely be used by us!

8

Nate 02.02.10 at 9:51 am

Thanks for the feedback, Erica. It’s high on our wish list too.

9

Ktopland 02.03.13 at 8:19 am

Hi
I am trying to solve my problem with Sigma/w , the problem is a braced – cut excavation that I simulate the model already but I have to use the uncertainty of soil property and non-soil also with COV and standard deviation. All input parametrs set are generated by Monte carlo in the excel I have to use 1000 generated input parameters in a row of excel to input automatically the input parameters of sigma/w . I try to save as my model .gsz to XML file to change some parameters value such as unit weight , modulus of soil ,cohesion etc. by copying all code in XML file and paste in to spreadsheet .Then I use some technic in excel to change values and remain format of code and copy it to paste in XML file then save. But I cannot to solve it after I changed in XML file. What I did wrong or please give me a technical to input values of parameter automatically 1000 of sets of input parameters . ( I want to find proabiltiy of exceedance of retaining wall with uncertainty of soil and non-soil)
thank you

10

Nate 02.05.13 at 5:47 pm

Ktopland, that sounds like an interesting technique you’re using. It’s hard to know why it can’t solve after you change the xml file without seeing an error message of some sort. I would suggest you use a file comparison tool such as WinMerge (http://winmerge.org/)–or perhaps an xml comparison tool such as DiffXml (http://diffxml.sourceforge.net/) would be better–to make sure you understand what you have changed in the xml file.

11

ktopland 02.25.13 at 10:20 am

hi
thank for your suggest
I have a few question on version 2007 v 7.10
1can sigma/w files(braced -cut excavation) be solved automatically by batch file? I followed what you explain how to solve several file by batch but did not work for my case
2 what code in the .cmd file to solve all stages of excavation and what code to output csv file ( I want to know the value of wall displacement at “final excavation stage” )

thank you for your kindness

12

ktopland 02.26.13 at 4:23 am

I solve several XML files by batch file

13

Nate 02.26.13 at 9:17 am

1. Yes, a SIGMA/W file should be able to be solved in batch just like any other. What errors are you getting?
2. To solve all analyses, use geostudio.exe "filename.gsz" /solve:all.

There is no way to output a csv file, but the .gsz file can be opened with WinZip, and it contains csv files. Or if you are working directly with the .xml file (no .gsz file), then the solver will write out all its results as csv files in a subdirectory with the analysis name.

14

Ktopland 02.26.13 at 9:32 am

I got error as below
when i double click directly the XML file .The solver opened then the error message show ” cannot read the results file required to solve this analysis” and ” File not found: C:\Users\ktopland\Desktop\case sena ok\2case sena.xml\final excavation to -6.9\2case sena.xml”

thank

15

Nate 02.26.13 at 9:37 am

And does that error make sense to you? Does “C:\Users\ktopland\Desktop\case sena ok\2case sena.xml\final excavation to -6.9\2case sena.xml” exist? It sounds to me like one analysis gets its initial conditions from another, but it can’t find that other analysis.

16

Ktopland 02.26.13 at 9:44 am

But when I right click the xml file and choose the open with “geostudio 2007” application. The xml can be opened and can be solve by solve analysis function .

I have to do like this I mean I work directly with xml files because I want to know sensitive analysis and I have several hundred files . I cannot input thousand of input parameters values , so I create xml file instead of gsz.

17

Ktopland 02.26.13 at 10:07 am

Finally I creat .cmd file(“C:\Program Files\GEO-SLOPE2007\GeoStudio2007\Bin\geostudio.exe” “C:\Users\ktopland\Desktop\5RFEM\case sena OK\16case sena.gsz”/solve:all ) for solve when I double click .cmd file . The geostudio.exe open but not solve and DOS show some text as below :
C:\Users\ktopland\Desktop\5RFEM\case sena OK>๏ปฟ”C:\Program Files\GEO-SLOPE2007\
GeoStudio2007\Bin\geostudio.exe”
The filename, directory name, or volume label syntax is incorrect.

C:\Users\ktopland\Desktop\5RFEM\case sena OK>”C:\Users\ktopland\Desktop\5RFEM\ca
se sena OK\16case sena.gsz”/solve:all

What error with me
thank you

18

Nate 02.26.13 at 11:12 am

Make sure there’s a space between the filename and the /solve:all.


"C:\Program Files\GEO-SLOPE2007\GeoStudio2007\Bin\geostudio.exe" "C:\Users\ktopland\Desktop\5RFEM\case sena OK\16case sena.gsz" /solve:all

19

ktopland 02.26.13 at 11:49 am

I copied your code to batch but still error

thank you

20

ktopland 03.07.13 at 8:36 am

Hi
Could I model the building frame structure that adjacent the braced-cut excavation and model the pile foundation under the frame structure ?
How can I do what I asking you?

I want to analysis displacement of pile and building distortion.

thank you

21

Nate 03.07.13 at 8:46 am

@ktopland: I’m not able to help with questions about modelling. I suggest you email support [at] geo-slope [dot] com, and one of our engineers will respond.

22

ktopland 05.01.13 at 11:23 am

hi
Can Sigma/w analyse pile settlement in case of point load is applied on pile ? (pile assume in soft clay with cohesive and modulus )

23

Nate 06.26.13 at 3:51 pm

ktopland, I’m so sorry for the late reply. I just noticed that my comment notifications were going to a spam box that I don’t check often. 🙁

Your question is beyond my limited engineering knowledge, but I checked with another engineer here and he says the answer is “yes”. Good news! 🙂 If you need more clarification, I suggest you contact support [at] geo-slope [dot] com.

24

Pi 01.08.14 at 5:01 am

For ones who may have problems with running analysis automatically from *.bat file which solves analysis titled “0.10G_Newmark” (remember that the right path should be placed):

“C:\Program Files (x86)\GEO-SLOPE\GeoStudio2007\Bin\GeoStudio.exe” “D:\XVW_010_20100626.gsz” “0.10G_Newmark” /solve /log:log.txt /autorun /autoexit

25

Pi 01.08.14 at 5:16 am

Where I can find Boudary Conditions for each node in xml file?

I want to assign different Boudary Conditions for nodes. At the moment the program assign the same acceleration history for all nodes at the bottom of the model which are fixed in the X and Y direction which is called uniform kinematic excitation).

My plan is to put for example 3 different accelerograms respectively for 3 bottom nodes (non-uniform kinematic excitation).

I’ve found the fragment of the xml file where I see the acceleration history as following:

2

boncon.acc
boncon.acc
m/sec/sec

26

Nate Hekman 01.09.14 at 10:15 am

Boundary conditions on the xml are in a . There’s one per analysis, which ties together the various global objects for that analysis. For example, find a whose matches the number of the analysis you want to work with, then look at its section to see all geometry items (points, lines, regions) that have a hydraulic boundary condition applied.

For example, this xml indicates that in analysis 1, point #12 is assigned boundary condition #3.

<Contexts Len="1">
  <Context>
    <AnalysisID>1</AnalysisID>
    <GeometryUsesHydraulicBCs Len="1">
      <GeometryUsesHydraulicBC ID="Points-12" Entry="3" />
...

27

Pi 01.08.14 at 5:17 am

2

boncon.acc
boncon.acc
m/sec/sec

28

Pi 01.08.14 at 5:20 am

sorry, I have problem with pasting the source code……
but I see PGA values which I can freely change.
I search for the link whre the nodes downloads the values.

If each node has this feature I can put whatever values I imagine.

Thanks for help.
Pi

29

Pi 01.13.14 at 6:27 am

Thanks for reply.

The problem did not disappear because I still cannot change the file in the way I want. These tips You wrote are useful indeed but the code allows only to change the boundary conditions in the line:

BC ID=”1″ Name=”Fixed X” Color=”RGB=(192,0,0)” XDisp=”Constant(Value=0,BType=X-Displacement)” YDisp=”Constant(Value=0)”

so that XDisp can be modified in a very limited way.

Of course i see that every line in my model has assigned BC. (ex. line #1 has BC. of number #2 – which is Fixed Y) but it refers to the line writen above which doesn’t tell anything about the place from where the acceleration values are taken.

The acceleration values are written in the Quake Object fragment and I don’t know how to paste another acceleration time history that can be treated as additional boundary condition and what is more how to force the geometric lines to absorb the second time acc. history.
I’m afraid that BC. in the form of a list (consisting of the acceleration values) is assigned defaultly somwhere else in somewhat file….

🙂

30

Soroush 11.19.14 at 2:19 pm

hi, please help me
how i can model a retainig wal in geostudio??
in seep and sigma especially..
it is very necessary to know.
thank you very much

31

Soroush 11.19.14 at 2:20 pm

excuse me .. retaining wall

32

Nate Hekman 11.24.14 at 10:52 am

Soroush, we have a few sample files on our web site demonstrating retaining walls. Each sample includes a .gsz file but also a pdf describing the thinking behind the approach. Hope that helps!

33

Muqdad 08.09.16 at 7:07 pm

Hi Hekman,
I now work in seepage analysis of concrete dam using SEEPW , I have to run many different hundred scenarios for this problem, which is time consuming ?
can you please show me how can I use Addin to run many file together and do you have the source code to SEEPW.

Thanks so much
Muqdad

34

Muqdad 08.09.16 at 7:41 pm

continue …
for each scenarios I have to change the problem geometry the boundary condition values and the soil parameters?

35

Nate Hekman 08.10.16 at 7:35 am

Add-Ins won’t help for running hundreds of scenarios, and they don’t allow changing geometry. I would recommend writing some code to manipulate the .gsz (or actually the .xml inside the .gsz) directly. It looks like you’re trying that approach as well: that’s the right way to go. Depending on your programming abilities, you can create some very elaborate changes using batch files, PowerShell, C#, or other tools.

36

Nida 08.31.16 at 5:50 am

i am using geo slope 2007, for the stability of the slope, but the shape of the slice isnt circle but ellipse, as far as i learnd bu the manuals this is because of an option of optimization which doesn’t make the traditional circle shape but it takes an ellipse form, i wont to change it but i dont know where

37

Nate Hekman 09.01.16 at 10:34 am

You can change slip surface settings on the Slip Surfaces tab in KeyIn Analyses.

Leave a Comment

You can use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>