Sheet pile retaining walls
Sheet pile retaining walls
(OP)
I am designing 25 metre high anchored sheet pile retaining walls. This high is well beyond the range that both the Australian AS 4678)and British BS8002)retaining wall design guidelines say they cover(up to 15 m).The walls are in a marine environment and are founded in very stiff clay. Any suggestions of particular design issues that may arise that are not covered by the codes of practice. Analysis is being carried out using Geosolve WALLAP retaining wall design program.





RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
different.
Both drained & Undraind testing
Sensitivity and remoled strength
Consolidation
sand seems or varves
local knoweledg
On some overly consolidated clays they can actually expeienc a loss of strength as it drainsdrain
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
I would presume that the anchor sheet piles are driven to 33 m as well for this system to function adequately. In effect this would reduce or increase the lateral pressures against the sheeting closest to the excavation. Increase if the system is designed as a double wall cofferdam. I am guessing here in the absense of further details.
If otherwise then one level of tiebacks would hardly be sufficient but if three sets of reviewers have okayed design, then they woyuld have taken concerns into consideration should be okay.
Basal heave my be a problem that needs to be checked through swelling. Seepage via fissures in the stiff clay could occur and this has to be of concern to basal stability. Stiffness of sections used etc
Some additional info would help. As information that may be reviewed, a couple of articles may be of assistance which you probably have used already. These are:
The design of and construction of Sheet-Piled Cofferdams by B.P Williams and D. Waite CIRIA special Publication 95.1993 Provides some detailed eworked examples. The other is Proceedings of the Conference on design and Installation of Pile Foundations and Cellular Structures which is referenced in first textby Fang H.Y and Dismuke T.D Proc Conference Lehigh University USA, 1970, Enviro Publishing Co. Inc
RE: Sheet pile retaining walls
Often less expensive pound for pound, pipe is used with fabricated interlocks typically consisting of a smaller pipe with a slot cut in it and a "Tee" which is a small wideflange cut in half.
The section modulus of a pipe can be huge and adjusted according to the diameter of the pipe and the wall thickness.
Also, for the company installing the retaining wall driving sheet piles 25m (or in this case more than 25m) is not easy especially in stiff clays as you describe. The open pipes with the interlocks acting as "fins" drive very straight and are less problematic in my eyes.
They can also be filled with concrete or other material as required.
This may reduce a significant amount of cost in material, and time for installation.
It will most likely still need some sort of waler and anchor system however but this may simplify things.
Please refer to the following links for more details:
http://www.giken.com/int/st/index.html
(note that the tubular sheet piles are not propriotary despite what some companies imply)
There also used to be details on the Nippon Steel webpage however I cannot find the link.
RE: Sheet pile retaining walls
Have you considered scour and extreme low water level during storm surge?
I also think driving 21m in stiff clay should be tested first.
VOD
RE: Sheet pile retaining walls
RE: Sheet pile retaining walls
Thank you
RE: Sheet pile retaining walls
Your case is not unique. It has been done in the past. I have extensive research in this regard. The following publication may help you (case history):
Bjerrum, L., Kenney, C., and Kjaernsli, B. (1965). “Measuring Instruments for Strutted Excavations,” Journal of the Soil Mechanics and Foundations Division, SM1, p 111-140.
Soil strength=400-800 psf
Dimensions of excavation: Length=38, Width=36, Depth=89
Number of strut levels: 3
Location: Gronland 2, Norway
Also there is another paper by [Hsing and Berman (1953)]. I think they had an excavation 19 meters deep in Chicago in medium stiff clay.
Good luck