Lateral Subgrade Reaction for Rock

[olalee]

I am making a model to analyse the pile, I need to have value of the "Lateral Modulus of Subgrade Reaction of Rock" in order to model the spring support, can anybody give me information about this. I have a book called ' Foundation Analysis and Design by J.E Bowles', it only gives me info for different types of soil. Please suggest another literature!! Thanks

 

[Focht3]

Please describe your problem in more detail so that we can give you appropriate guidance.

Please be aware that the modulus of subgrade reaction is not an unique property; it is a factor of convenience. "The" modulus of subgrade reaction for any soil or rock does not exist.

 

[olalee]

My problem is: I am making a portal frame (an integral bridge model including deck, abutment and piles) with spring support at each layer of soil around the pile.

For the spring support, I need to input a spring constant for representing the type of soil I have, and it is measured in the unit of (Force per unit displacement). Therefore, I think the use of lateral modulus of subgrade reaction is appropriate, (I am interested in getting the lateral movement of the portal frame!!).

I have already got a range of lateral modulus of subgrade reaction for several types of soil, but I need the same information for the rock. Please advice!!

 

[olalee]

The main objective of the portal frame model is to obtain the moment and shear force for the piles, abutment and at the joint of the deck, so that I can design these element.

 

[Focht3]

Where is the site? How big is the bridge? Have you talked to your geotechnical consultant? What did he/she say?

Unless your bridge is a small, seldom used pedestrian bridge with a very short span and located over a normally dry creek, simply assuming values is an extremely foolish undertaking. Hell, it's foolish even then. Forget Bowles' book - it's about to get you in trouble.

Sounds like you need the help of a competent geotechnical engineer familiar with your area.

 

[Murrell]

'Olalee'

I am currently setting up an integral bridge model, and have the same problem that you had in determining the lateral modulus of subgrade reaction for chalk.

Out of interest, how did you overcome this problem in the end?

 

[Murrell]

'Olalee'

I am currently setting up an integral bridge model, and have the same problem that you had in determining the lateral modulus of subgrade reaction for chalk.

Out of interest, how did you overcome this problem in the end?

Any advice would be much appreciated!

 

[dirtbag]

If the lateral capacity of a pile embedded into rock is exceeded then the pile will break off at the rock/soil interface (assuming the rock compressive strength exceeds the strength of the pile). The pile should be modeled with a point of fixidy at this interface. modulus of subgrade reaction for rock will be infinite when compared to soil.

 

[BigH]

Don't have it with me, but check out Tomlinson's book on Pile Foundation and Design. He has a good chapter on lateral loading of piles - likely in rock/chalk too as he is a Wimpey-man.

 

[wavequest]

Pardon the "non-helpful" email... but are you Olalekan G. from Nigeria. If so, this is Matt from U of H. Reply and we'll exchange email

 

[Focht3]

Matt: (aka wavequest)

If you are/were at the University of Houston, perhaps you know Dr. Michael W. O'Neill in the CE Department. Mike is very knowledgeable about p-y curves, and might help you to help your friend with his problem. He could at least suggest a few references -

Anyway, it's a thought.