Segmental Retaining Wall, Software

[anchorengineer]

Does anyone know if segmental retaining wall programs take into account the stone behind the wall (used for drainage) when it gives you a geo-grid lenght? I was going to add an additional 1 foot of length but didn't want to overdo it.
Thanks.

Clarke Engineering Services, PC
Jobsite Engineering and Consulting

http://www.anchorengineer.com

 

[RFreund]

I'm not sure if you have a particular program in mind, but normally there is no additional grid length needed because of the drainage aggregate. The program most likely does not directly account for drainage aggregate but I don't think it should. A few reasons why off the top of my head:

The drainage aggregate effective friction angle (phi) and unit weight is likely the same or greater than the reinforced soil. To develop the 'bond' from grid to soil you must be beyond the failure plane which is beyond the drainage aggregate.



EIT

 

[anchorengineer]

EIT,
Those are good points. I have one section of wall that has the geo-grid at the second course of block from the bottom and there is some interseciton but the amount that it would affect the wall will be very small. The program I'm using is Retain-pro. I emailed tech support and the engineer said he had to check on this...
Thanks for you help!

Clarke Engineering Services, PC
Jobsite Engineering and Consulting

http://www.anchorengineer.com

 

[RFreund]

I have not used Retain-Pro, however I'd be interested in their answer.

Also I'm not quite sure what you mean by "there is some intersection". If you would like to provide a sketch or try to clarify, I can try to give you my opinion. Or just wait and see what Retain-Pro has to say.

No Problem!

EIT

 

[anchorengineer]

I have a 1.5:1 slope behind the wall and the rankine angle is pretty sharp. I'll let you know how retain-pro responds.Thanks again.

Clarke Engineering Services, PC
Jobsite Engineering and Consulting

http://www.anchorengineer.com

 

[concretemasonry]

anchorengineer -

May get a quicker and more practical answer if you contact the most probable supplier of the units. the major 4 brands (Allan Block, Anchor Wall Systems, Keystone and Versalok) all have over 25 years of international and domestic exposure and experience and testing for various state and international authorities. You may not want a truckload of reports, but they have the real concise answers for a question similar to yours.

It is ironic that these 4 firms did rely on a firm called Clark Engineering (my classmate was a principal) and other engineering firms for consultation about 20 years ago.

If you have an off-brand/knock-off product, the geo-grid connections and shear resistance may not be able to be verified by performance.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[RFreund]

I agree with Dick that the big manufactures are very helpful.

However now I'm confused on what your evaluating. If you are evaluating external (sliding/overturning) and internal (pull-out, connection, sliding, overturning) stability. I don't see how the drainage aggregate is effecting the calculation (besides that it disrupts the assumed failure plane). How wide is the drainage aggregate? How wide and tall is the block? The grid length should be a minimum of 4 feet (NCMA minimum).

So if I understand this correctly at the first layer of grid, the grid is beyond the failure plane by 1 foot (this is another NCMA minimum) and still in the drainage aggregate?

EIT

 

[concretemasonry]

The major SRW firms are more in tune with the engineering and usually write or approve the NCMA and other standards because of their broad experience and willingness to give the engineering information because of the similarity of the systems that are licensed to qualified producers.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.