2. COFFER DAMS AND
CAISSONS
Presented By:
• M. Rizwan Riaz 2011-MS-CES-01
(rizwansamor@gmail.com)
• Muhammad Ammar 2011-MS-CES-34
Presented To:
Prof. Dr. Aziz Akbar
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3. CONTENTS
The discussion is divided into the following sections :
• Coffer Dams
– Introduction
– Types of Coffer Dams
– Environment Friendly Coffer Dams
– Case Study
• Caissons
– Introduction
– Types of Caissons
• References 3
4. Coffer Dams
• A temporary structure designed to keep water and/or
soil out of the excavation in which some structure is
to be built.
• When construction must take place below the water
level, a cofferdam is built to give workers a dry work
environment.
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11. Environment Friendly Coffer Dams
(Portable Coffer Dams)
• Instead of using outdated sand bags and
earthen fill, “DamitDams” patented water-
filled cofferdams
• Made of a heavy-duty geotextile woven
polypropylene outer casing that contains
two side-by-side inner tubes.
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15. Portable Coffer Dams
• Effective water-barrier dam leaving only a
minimal footprint on the environment.
• Use onsite water
• Portable and re-usable.
• Available in eight different heights: 1-2-3-4-6-8-
10 and 12 feet.
• Can be extended to any length necessary, using
the extension coupling system
• Flexible, easy to install, steer or turn precisely
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24. Rehabilitation Project
• Scope:
– Construction of Sub-Weir D/S of Old Structure
• Contractors:
– Descon Engineering Limited & Chinese Gazooba Corporation
• Duration :
– 2 years (October-June)
• Cost:
– Subweir Construction PKR 3 billion
– Coffer Dams Construction 700 million PKR
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27. Cofferdam Cross Section
• Stone fill was provided to break the erosive
action of the flowing river (design velocity of
8-10 fps was used to compute the stone size of
≥100lb)
• Earthfill was provided for a water tight section
minimizing the water flow across CD body.
• Sheet Piles were installed to cut seepage rate
across the earthfill and improve its stability.
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28. Construction Methodology and
Compaction
• The construction in flowing water was carried out
by means of heavy machinery like dozers, dump
trucks and excavators, weighing from 10 to 15 tons,
moving freely on top of the newly constructed
embankment.
• The stone dump was constructed in advance of the
earth fill embankment which was constructed in its
shadow.
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34. Quantities of Material used in Phase I
• Earth Filling =11.46 M cft (324,394 m3 )
• Stone = 100,000 cft (3000 m3)
• Sheet Piles Area = 224,000 sft
• Depth = 35-40 ft
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Stock piles maintained at site to ensure un-
interrupted supply.
35. Dewatering
• Dewatering required surface water removal and
lowering of the subsurface water levels.
• The operation required installation of a large
number of tubewells along with pumps and screens
in the substrata
• Dewatering in the subweir area was the most
demanding and critical to construction work.
• Detailed seepage analyses were carried out to
ensure required water levels.
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40. WHAT IS CAISSON?
It’s a prefabricated hollow box or cylinder.
It is sunk into the ground to some desired
depth and then filled with concrete thus
forming a foundation.
Most often used in the construction of bridge
piers & other structures that require foundation
beneath rivers & other bodies of water.
This is because caissons can be floated to the
job site and sunk into place.
41. Basically it is similar in form to pile
foundation but installed using different way
Used when soil of adequate bearing strength
is found below surface layers of weak
materials such as fill or peat.
It’s a form of deep foundation which are
constructed above ground level, then sunk to
the required level by excavating or dredging
material from within the caisson.
42. A caisson foundation consists of concrete
columns constructed in cylindrical shafts
excavated under the proposed structural
column locations
Caissons are drilled to bedrock or deep into
the underlying strata if a geo technical
engineer find the soil suitable to carry the
building load.
65. Caisson Disease
In case of sinking process of pneumatic caisson,
workers working under pressure may suffer from
“Decompression sickness” (Caisson disease) due to
rapid change in pressure
• There is pains in ears of workmen
• There is breaking of ear drums of workmen
• There is bursting of blood vessels in the nose
or ears of workmen
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66. Factors affecting choice of
Caissons
• Uneven applied loading & no firm strata at
reasonable depth, making use of raft unadvisable.
• Firm strata exists at such depth, where
construction of strip footing is uneconomical.
• Pumping of ground-water is costly & shoring is
difficult.
• Heavy load must be carried to water-logged or
unstable soil, where large number of piles with
large pile caps is uneconomical.
• Plan area of construction is small and water is
deep. 66
67. American Concrete Institute (ACI)
• American Concrete Institute (ACI)
committee 336 has two specifications.
1. Standard Specification for the Construction
of Drilled piers (Caissons)
2. Design & Construction of Drilled piers
(Caissons)
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68. American Petroleum Institute (API)
• American Petroleum Institute (API)
provides guidelines and specifications
for the Design & Construction of
offshore Caissons.
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75. References
• Muhammad Nadeem, “Cofferdam construction and dewatering
taunsa barrage rehabilitation project”, Pakistan Engineering
Congress, 71st Annual Session Proceedings, Paper No. 683.
• Ijaz-ul-Hassan Kashif, “Director proc & contract administration,
PMO Punjab Barrages, “Construction of small dams in Potohar
plateau of Punjab Province”
• www.en.wikipedia.org/wiki/File:OlmstedRendering08_2012.jpg
• www.theconstructor.org/geotechnical/all-about-coffer-dam
• www.donegan.co.uk
• www.ceephotos.karcor.com
• www.damitdams.com
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76. References (Caissons)
• Pile Design & Construction Practice (4th Ed.) by M. J.
Tomlinson
• Construction Technology for tall buildings (3rd Ed.) by M.
Y. L. Chew, Michael Chew Yit Lin
• Foundation Analysis & Design (5th Ed.) by Joseph E.
Bowles
• Pile Foundation Design & Construction by Dr. Gue S. Sew
• Deep Foundation Institute (www.dfi.org)
• Wikipedia (www.wikipedia.org)
• The Constructor Organization (www.theconstructor.org)
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Allow excavation and construction of structures in otherwise poor environmentProvides safe environment to work Steel sheet piles are easily installed and removedMaterials can typically be reused on other projects
www.donegan.co.uk
I.H. Kashif, CONSTRUCTION OF SMALL DAMS IN POTOHAR PLATEAU OF PUNJAB PROVINCE
Ref: Muhammad Nadeem, P.E.C, 71st Annual Session,Paper No. 683
This is the view showing the downstream weir which is to be built. To keep the river flowing, the work plan was to divide the work in low flow months in 2 years. Half of the weir was to be built in first year and the other half in second year. A total length of 12 km length of CDs was constructed during the project.Muhammad Nadeem, P.E.C, 71st Annual Session,Paper No. 683
Muhammad Nadeem, P.E.C, 71st Annual Session,Paper No. 683
Proposed coffer dam was hybrid type with following materials used
