Pile and Lagging Walls

[4n6]

I am looking for any references for the design of pile and lagging walls.

We are doing preliminary estimating for a project that involves a cut retaining wall to support poor quality native limestone (RQD = 0 -5). The cut structure will be just a few feet of of the property line, thus our first thought is a pile and lagging wall would be the best option.

We will be supporting limestone, with piles embedded in the smae limestone. Wall forces should not be that great, but weathering and deterioration of a cut face is the main concern.

Any ideas or references for rough design?

Thanks

 

[Focht3]

You need the assistance of a local geotechnical engineer who has a strong geology background. Your problem needs a site visit - and expert eyes. These are things that our on-line community cannot provide -

Good luck.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[GeoPaveTraffic]

I agree with Focht3. Also, there may be much better and cheeper alternatives than a pile and lagging wall.

 

[4n6]

Focht & GPave,
Thanks for the input. I agree with your comments. We will not be providing a design for this wall at this time - only providing rough feasability info to the client. As such we are just trying to get a grip on some ball park costs that might be associated with this structure. If these costs look o.k., the client will release us to put the "expert eyes" onsite and provide a detailed design.

Gpave, you mentioned a potentially cheaper alternative? I'd welcome your thoughts along that line. Our main constraint is the location of the wall & property line. Our wall is a cut, located approx. 5' from the property line. This eliminated MSE, and tieback walls, which are our usual preference from a cost standpoint.

Thanks for your help!

 

[CSEllc]

I hate to sound dumb, but I'm not familiar with the term MSE. What is it?

 

[Focht3]

Mechanically stabilized earth. Don't worry - the term only developed within the last 5 years or so - and still isn't "widely" used. Unless you do a lot of them, of course -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[CSEllc]

Thanks....

 

[GeoPaveTraffic]

The alternative that came to my mind would be a shotcrete facing on the rock. But a lot will depend on the depth of the cut the fracture/joint pattern of the rock etc.

The potential problem that I see with your situation is that you face to unappealing choices. First you provide a high estimate to stabilize the cut, you protect your self from being low, but in the process you price the project out of economic viability. The second is that you provide a best guess, the actual cost is much greater and the client is mad at you for being wrong.

This is the problem with providing estimates when not enough is know about the situation prior to making the estimate. Depending on your relationship with the client you may be able to sit down with them and discuss the problem and either get the go ahead to do more engineering on the potential solutions or they may just want the worst case.

 

[GabionGuy]

4n6,

Depending on the height of your cut and space constraints, you may want to consider the use of a gabion basket retaining structure. These systems can be very cost effective in cut situations.