I am designing MSEW wall. The wall

[bbac]

I am designing MSEW wall. The wall has slope of 6 degrees with vertical and it has 20m height, and a 2m wide berm at 10m depth. I am checking External stability, Global stability and internal stability. I use a slope stability program for checking global stability. Is it sufficient to use slope stability program also for checking internal stability (rupture and pullout)? Or do we need to verify rupture and pullout resistance for each layer by hand calculation, assuming a failure plane eg. coulomb`s active earth pressure case)?

 

[IDS]

Yes, you need to check pull-out and rupture for each layer.

If you are designing a wall of that size, and you are not familiar with MSE wall design, you really need to get someone involved who is experienced in this area.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[GeoEnvGuy]

First off I rarely see wall designers take on global stability. Secondly I don't see wall designers even using slope stability programs to design the wall. I do see wall designers use slope stability sometimes, not often, as a general check.

 

[IDS]

The standard procedure (at least in the areas I have been involved in) is that the wall supplier does the detailed internal design, using product specific software, and specifically excluding global stability.

That doesn't mean that the "wall designer" should ignore global stability. For a 20 m high wall global stability should certainly be checked by whoever has overall design responsibility for the project.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[bbac]

Thank you all for your answer.Actually i am not a designer myself but im reviewing the design from a supplier. Mistakenly i wrote earlier that i am designing.. The software which the supplier uses works on the concept of slope stability to check the internal stability. All the slip surfaces will be analysed which passes through the reinforcements and minimum factor of safety is the output.I would like to know if it is enough for the check for internal stability. What about your experience in this regard.

 

[MTNClimber]

No, that's not all you should check. The designer and reviewer should be checking:

Tensile stresses on the grid, anchor length/pull out,internal sliding, facing connection, crest topping, ect... plus normal external stability. If you aren't familiar with these, someone that is should be checking them. 20m is a huge wall for MSE which means large consequences.

 

[cvg]

drainage and granular/geotextile filter layer at the interface with the facing

https://www.geosynthetica.net/mse-wall-failures-geotechnical-filters/

 

[GeoEnvGuy]

I would like to know if it is enough for the check for internal stability.

No. More work is required.

 

[IDS]

I've just done an image search on retaining wall failures.

I'd recommend you having a look at that too, and note that almost all the tall wall failures are modular block MSE walls.

Then find someone with real experience of design and review of MSE walls of this height or greater.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[bbac]

MTNClimber (Geotechnical):As you said im checking internal,external stability,global stability.For internal stability for rupture and pullout, i prepared an excel spread sheet calculation, assuming Rankines failure plane. The software which the supplier is using doesnot include check for each layer of geogrid for rupture and pullout. Since the supplier claimed that their check for internal stability is sufficient,i got confused. Thank you all for your answer.