CONSTRUCTION CONSIDERATIONS Requirements, Different Construction Activities, Compaction Control Site preparation Diversion and coffer damming Foundation preparation Grouting Excavation Fill placement and Soil compaction

1. CONSTRUCTION
CONSIDERATIONS :
Requirements, Different Construction
Activities,
Compaction Control
Presentation by
UDAY KUMAR DEVALLA (MT17WRE002)
TULSHIDAS JIBHAKATE (MT17WRE003)
LAXMI MAROTI KHANDRE (MT17WRE004)

2. REQUIREMENTS
The principal requirement in the design of an
earth dam is to provide a structure at the
minimum cost which remains safe and stable
during all phases of construction and operation of
the reservoir

3. Technical requirements :
1. The slopes of the embankment must be stable
under all conditions of construction and
reservoir operation including sudden
drawdown of the storage reservoir
2. The embankment must be so designed as not
to induce excessive stresses in the foundation
3. The upstream slope must be protected against
erosion by wave action; the top crest and the
down stream slope must also be protected
against erosion due to wind and rain

4. DIFFERENT
CONSTRUCTION
ACTIVITIES
1. Site preparation
2. Diversion and coffer damming
3. Foundation preparation
4. Grouting
5. Excavation
6. Fill placement and
7. Soil compaction

5. Site preparation
a) Cleaning and grubbing
Cleaning:
Removal of trees, rocky stones ,
temporary structures etc.
Grubbing:
Removal of plant roots and organic
matter for the location of the borrow pits
(confined within the region of embankment )

6. Site preparation
b) Stripping :
Removal of all top soil , organic matter and
other soft pockets
c) Scaling :
Removal of loose overburden of weathered
rock and other weak material from the abutments

7. Diversion & Coffer
Damming
A coffer dam must be relatively low in cost but as a
watertight as practicable
Dump starting from
the abutments on the
both sides and
working towards
centre of the dam
Fig

8. Foundation preparation
The cutoff trench is dug as an open excavation
which carried out to sound rock level or other
impervious stratum.
It is normally a sloping side trench which is
excavated and back filled with a impervious
material, compacted in the same manner as the
impervious zone of the embankment.

9. Grouting
Grouting is injecting mixture of cement , water and
other admixtures like sand, clay and rock dust in the
subsoil formation
It serves two fold objectives
1. Make the formation impervious and
2. Improve its strength and compressibility
Grouting is done by filling cracks, fissures, cavities and
even voids between the soil grains with the grouting
material

10. Excavation
The excavation in barrow pits depends upon the type
of available materials and the positioning with respect
to soil moisture present in the pits
Following methods are generally used
1. Hand excavation
2. Power shovel
3. Drag line
4. Scrapper
5. Elevating grader

11. Fill placement
Material handled by Dumped in
Hands Small pits
Truck or wagons Uniformly spread piles
Scrapers Uniformly thin layers of the thickness
of its blades
Bulldozers or road grader Uniformly in piles and wind rows
In-place processing:
Involves mixing of two materials such as impervious clay
(in small amount ) with less water tight sandy soils ( in
large amounts ) as in core construction

12. Soil Compaction
Compaction is the process by which the required
density of the soil in the embankment can be attained
Compaction of the soil materials is carried out by
rollers which are of the following types
1. Sheeps foot roller
2. Heavy pneumatic tired roller
3. Vibrating roller
4. Crawler type equipment e.g tractors
5. Ordinary pavement rollers

13. Compaction Control
The field engineer has to
make periodic checks to see
whether the compaction is
giving desired results.
The procedure of checking
involves
1. Measurement of dry unit
weight
2. Measurement of
moisture content

14. Different methods
Fill water content
Direct Heat Chemical
1.Laboratory Oven
Speedy moisture
2.Laboratory Microwave
3.Gas Stove
4.Moisture Analyzer
Fill unit weight Fill unit weight and water content
1.Sand Cone test (SCT) 1.Moisture Density
Indicator(MDI)
2.Water Balloon (WB) 2.Nuclear Density Gauge (NDG)
3.Steel Shot (SS) 3.Soil Density Gauge (SDG)
4.Electrical Density Gauge

15. Sand Cone Test
The sand cone apparatus is formed by a jar made
of plastic or glass with a metal cone attached to its
top. The jar is filled with a reference sand

16. Water Balloon Test

17. 1
2
3
4
5
6

18. Nuclear Density Gauge
It is used to obtain the in situ dry unit weight and
the water content

19. Principle:
The test is based on the following principle: the
amount of gamma rays counted by the
equipment during a certain period (usually 1
min) is inversely proportional to the density of
the material
The equipment is composed by three main elements:
1. A nuclear source - responsible for the emission of
gamma rays or neutrons
2. A radiation detector
3. A counters with provisions - to detect an automatic
and precise timing for the arrival of the modified
gamma ray.

20. Nuclear Density Gauge
Density:
Source emits Gamma rays
Water content:
Source emits Neutrons

21. Nuclear Density Gauge
Two modes

22. References :
1. Elements of water resources engineering by KN Duggal & JP Soni
2. Geotechnical engineering by VNS Murthy
3. Geotechnical engineering by Venkataramaiah
4. https://run.unl.pt/bitstream/10362/16025/1/Blanco_2015.pdf
5. https://labmekanikatanah.wordpress.com/2013/10/29/field-
test-rubber-balloon-method/

23. THANK YOU