TITLE:
Theory of Combined Seepage Applied to Dewatering Systems
AUTHORS:
Magdy M. Aboelela
KEYWORDS:
Confined Seepage, Unconfined Seepage, Combined Seepage, Sheet Piling Cofferdam, Seepage Discharge, Phreatic Surface
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.8 No.7,
June
24,
2016
ABSTRACT: In the
present study, an analytical solution is presented to solve the problem of combined
seepage, under a sheet piling cofferdam, applied to dewatering systems.
Existence of the sheet pile creates a confined seepage followed by an
unconfined seepage in the same field, which presents a combined seepage
problem. Two equations were developed to analyze the combined seepage
underneath a sheet piling wall. Using such equations, both the maximum height
of the free surface just behind the sheet piling cofferdam (Ho) and the quantity of
seepage discharge to be pumped out from the construction site (q) can be determined. The main
parameters affecting the combined seepage characteristics underneath a sheet
piling wall are: The depth of permeable foundation layer (T), the horizontal distance behind the sheet pile (X), the depth of excavation in the
construction site (D), the embedded
depth of sheet pile (S), the retained
water head (H1), the
accumulated seepage water depth (H2),
and the side slope factor of excavation line (M). Study showed that, the above parameters have a great effect on
the combined seepage, but with different extents.