Soldier Pile Embedment into Rock

[bailey]

I am designing a soldier pile and lagging wall adjacent to a railroad. The excavation will be about 22ft deep and to rock. The rock is grey shale with about the top 5 ft weathered. Below this, the rock is fairly competent (RQD~75%-85%), and have assumed that the pile is fixed here.

Where can I get information to determine how deep the pile needs to be embedded into the rock?

 

[gandersen]

bailey:

One method to determine the depth of embedment is to model the lateral resistance and strength of the rock mass and to vary the depth of embedment until the lateral deflections and deflected shape are suitable. This is really the job of a geotechnical engineer using a analysis program such as L-Pile. I would recommend a geotechnical engineer be engaged to help you.

For a quick answer, you could ask around and see what local practice is for the bedrock configuration and height of retaining wall that you have.

Glen

 

[VAD]

From the information provided,it seems that you have undertaken a geotechnical investigation. Another question you may ask is how do I achieve desirable embedment in rock. I would presume that you may have to drill into the rock. On the other hand you may wish to consider raker piles, if there are no constraints. However, ganderson has provided the approach that needs to be taken.

 

[BigH]

For point of fixation, etc., see Polous and Davis Pile Design book - they have a good section on anchoring into rock. Wiley book.

 

[cap4000]

I have looked hi and low for your situation into rock sockets. The conclusion I have come too is that there is NO books that directly answer your question. Ensoft,Inc has an LPile program that may assist you. As far I know there are no "k" values for rock. What I have done in the past is design the socket as a Fixed End. If you can, drill a couple of holes and experiment to see the best 22 foot high H-Pile/Lagging results.Raker Brace Beams and a Finte Elment Analysis Program is my prescription. Good Luck.

 

[Focht3]

The answer you seek cannot be found in a text book. While the Poulos & Davis reference is a good one, the problem that you are dealing with is not a straightforward one. You need to turn this one over to an experienced geotechnical engineer; your description of the shale as

...grey shale with about the top 5 ft weathered. Below this, the rock is fairly competent (RQD~75%-85%)...

tells me that "rules of thumb" may not apply to your situation.


Hire an expert. After all, you don't want the wall to fail -



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?"