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Hydraulic Performance - Transmissivity and Permeability | Mike Yeats | |
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2004 |
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The movement of water can severely sabotage an engineer's
efforts by degrading the strength of underlying soil and
causing washout of structures, or by transporting chemicals
to unwanted locations.
The long-term transmissivity and permeability capabilities of
CMI's vinyl sheet piling are outstanding due to their corrosion
and chemical resistance, lower cost, and tight interlocks,
which have been designed to utilize the latest in sheet piling
sealants. The ability to reduce flow is further enhanced by our
full box section sheet piling, which have 50% fewer interlocks
than conventional sheet piling.
Casagrande, using conventional flow net techniques,
evaluated the ability of sheet piling to cut off water flow. The
evaluation revealed that the efficiency of a cut-off wall was
related to both the percent open area and the distribution
of the interlocks.
The cut off efficiency will therefore be higher when the
interlocks are broadly spaced. CMI's two-foot-wide full box
sheet piling offer a 20% higher cut off efficiency versus
typical sheet piling.
Geotechnics, an independent laboratory, measured the rate
of water flow through our sheet piling interlocks. The results
of testing for groundwater heads up to 32 feet fell within
most regulatory tolerances. While the leakage through the
standard interlock is minimal, applying a hydrophilic sealant
will reduce the flow to an even greater extent.
Interlock Sealants
The use of hydrophilic sealants in the interlocks of sheet piling
has been a common practice for many years. The ability of
the sealant to expand several times its volume when coming
in contact with water can effectively seal the interlocks. Sealants form Adeka Ultra Seal are available in paste form,
P-201, or a two-part liquid form, A-30.
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P-201 One-part system available in tubes
Cure time is temperature and humidity dependent
Does not require interlock ends to be taped or pilings to be
level
Two times expansion by volume
Approximately 120 feet of interlock coverage per gallon
A-30 Two-part system requires mixing prior to application
Quick cure time, even in sub-freezing temperatures
Pour able consistency of heavy oil
Interlocks must be level and ends taped
Three times expansion by volume
Approximately 130 feet of interlock coverage per gallon
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