Seepage through sheet piles 6

[GeoGnome]

I am looking for an estimate of seepage through the joints in sheet piles.

 

[PEinc]

Try getting information from Skyline Steel and check their web site. See following page:

http://www.skylinesteel.com/products/sheet_piling/default.aspx

 

[GeoPaveTraffic]

Keep in mind that the seepage through sheet piles depends greatly on the stress in the sheet piles. For example if you drive a single line of piles for use as a cut off wall the seepage will be around 10^-5. However, if the piles are heavely stressed then the permability may be as low as 10^-9.

 

[GeoGnome]

Thanks for the prompt responses. The Skykine site has a paper on the subject reflecting experimental results for sealed and non-sealed joints. You need to register with them to read it. The paper also talks about applied pressure difference.

I subsequently found a mention in an old version of NAVFAC DM-7 where it says "the quantity of water passing through intact interlocks may be as much as 0.1 g.p.m. per ft of wall length for each 10 ft differential in head across sheeting, unless special measures are taken to seal interlocks."

 

[PEinc]

Remember that hot-rolled sheet piles have tighter interlock than do cold-formed sheet piles. If you are trying to control water seepage, go with hot-rolled sheets.

 

[GeoGnome]

I wasn't aware of this. Could you tell me why?

 

[PEinc]

Cold-formed sheets have just a rolled-over hook-like interlock that is very sloppy. Hot-rolled sheets have tighter interlocks where a male end fits inside a female end. Look at Skyline's hot-rolled AZ sheets and Casteel's cold-formed sheets. Both should be on Skyline's web site.

 

[PEinc]

Cold-formed sheets are not recommended for water-tight cofferdams. Their interlocks are too loose and sloppy.

 

[Panars]

I worked on a project for the US Army Corps of Engineers, Pittsburgh District a number of years ago where I needed to estimate the volume of seepage through a sheet pile cutoff wall. I found very little information on the subject. I ended up using the reference you found in NAVFAC.

 

[BigH]

There are a number of good references you can get through a net search. Look up "Hoesch" steel sheet piles - they have a manual that discusses in some detail this problem (pages 10 to 12) - and it gives a worked example of the computation to determine the interlock seepage resistance. They also give information about this value for theirs as well as other's sheet piling (e.g., Larssen). I saved the manual but didn't note down the URL - sorry but the title of their manual is: "HOESCH steel sheet piling. Interlock sealing systems" (ThyssenKrupp GfT Bautechnik - may try

http://www.tkgftbautechnik.com

- or ww.steelsheetpiling.de). Also Pile Buck, on one of their web pages suggests you use "at least 1.5 gal/hr/sq.ft. of wall/ft. of net head across the wall for installations in moderately to highly permeable soils." (

http://pz27.pilebuckinternational.com/design/seepage.php

)

 

[PEinc]

Nice, BigH.

 

[DRC1]

The sepage through the sheets in dams entirely in soil is generally low and is easily contolled by pumping. Most of the inflow is underseepage which is generally estimated by flow nets. Flow calculations are a best guess analysis, and pumping should be designed to handle more than the calculated amount. On the plus side, after a few days of pumping, soils will often tighten up and flows decrease. Whwn working in open water, Saw dust or oats can be sprinkled around the outside of shallow dams(10-25 ft deep) to decrease the flow in the locks.

 

[SlideRuleEra]

Adding to comments by DRC1, I have been told by "old-timers" that another common product to help seal the interlocks is rice. It sinks when put in water, but the grains that get drawn in soon swell to cut down seepage. The downside, is that the more successful any of these "sealing" materials (saw dust, oats, rice, etc.) the more difficult it is to extract temporary sheeting - the sealants tend to prevent disassembly.

Good links, BigH.

http://www.SlideRuleEra.net

 

[PEinc]

Cinders have been frequently been used to seal the interlocks where only water is behind the sheeting. Unfortunately, cinders are getting hard to find.

 

[GBTDS]

There are a few commercially available products out there that help to seal the interlocks - one is WADIT which is made in Germany but distributed in the USA. The other is BIGUMA which I have only seen in Europe.
Both you have to manually place in the interlocks before threading the sheets together (a problem if you are having pairs of Z sheets delivered from a supplier).
The other advantage is that with the sealant in the interlocks, sand does not intrude thus reducing the friction and binding that often occurs during installation.

 

[GBTDS]

Also look at

http://www.waterloo-barrier.com/

- they have been involved in sealing interlocks INCLUDING cold-formed for many years.

 

[cvg]

I have even heard of straw and horse manure being used to plug leaks - in dams that eventually failed...