Bearing Capcity for Soft Clay over Stiff Clay
Bearing Capcity for Soft Clay over Stiff Clay
(OP)
I am looking for references or equations to compute bearing capacity for layered soils.
I have already looked up the following and looking for some more......
1. Myerhoff & Brown, 1960 Geotechnique
2. Myerhoff & Hanna, 1973 Geotechnique & Das's Book
3. Vessic 1973 (Winterkorn and Fang)
4. Army Corps Shallow Foundation Manual
5. Navfac Shallow Foundation Manual
Are there any other sources..........
I have already looked up the following and looking for some more......
1. Myerhoff & Brown, 1960 Geotechnique
2. Myerhoff & Hanna, 1973 Geotechnique & Das's Book
3. Vessic 1973 (Winterkorn and Fang)
4. Army Corps Shallow Foundation Manual
5. Navfac Shallow Foundation Manual
Are there any other sources..........





RE: Bearing Capcity for Soft Clay over Stiff Clay
RE: Bearing Capcity for Soft Clay over Stiff Clay
There is a procedure in AASHTO Standard Specifications for Highway Bridges 2002/17th Edition. I don't have the LFRD edition, but I can only imagine that they would have it in there as well. I don't know where they got it from.
Hope this helps,
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: Bearing Capcity for Soft Clay over Stiff Clay
I am calculating bearing capacity for 22 feet wide retaining wall footing embeded 3 feet over a soil layer that has a strength of about 500 psf (4 feet layer) over 1500 psf. Each one of the methods result in different answers. Meyerhoff and Hanna (Das' book) results in twice the value of (Vesic 1973; Winterkorn and Fang) and AASHTO LRFD's manual (ref; EPRI 1983- Electrical Power Research Institute).
So I called up Dr. Das, He believes EPRI 1983 which is in AASHTO is an improved on Vesic 1973; which is based on semi-emperical theoretical calculations. He believes Meyerhoff and Hanna because they came up with those equations by conducting lab tests in using a box.
I am confused on which equation is appropriate. My google research tells me there are onging studies conducted in several countries including India, Australia, etc. till 2005.
Is there a study out there that does a parametric study /review of each method and its applicability?
Sincerely
Indyhans
RE: Bearing Capcity for Soft Clay over Stiff Clay
RE: Bearing Capcity for Soft Clay over Stiff Clay
I tend to agree with comments made by BIG H re the soft clay layer. Here are some of my comments.
It appears that you are building a wall that is vey high 50 ft at least based on the base width chosen or you are trying to invoke the lower stronger layers in your bearing capacity evaluation, or on the other hand you are concerned about settlement and have used a wider base. This has the effect of invoking characteristics of layers with depth, at least 1.5 times the footing width based on classical theory.
It may be that you are building an MSE wall, even so the base width suggests a tall wall.
Based on some quick calculations it would appear that if you do not want to remove the soft layer then your wall height for an FOS of 1.5 in BC would would have to be no greater than between 12 and 15 ft. and perhaps as low as 10 ft re BiGH's comments of the weak layer governing.
It is always of interest to see the variations one obtains using different equations in the literature and the uncertainty of which one to choose. That is the beauty about geotechnical engineering. Finally, you have to make the judgement call which ranges somewhere between optimistic and pesimistic values and invokes other concerns as well. Settlement issue could be a concern for both cantilever and MSE wall types. This has to be considered as well.
Removal of the weak layer is a solution if wall is to be much higher or other types of foundation improvement-short piles, stone columns, stone cement columns etc. The choice will depend on site factors/considerations.
RE: Bearing Capcity for Soft Clay over Stiff Clay
RE: Bearing Capcity for Soft Clay over Stiff Clay
RE: Bearing Capcity for Soft Clay over Stiff Clay