This document discusses engineering geology considerations for dams and reservoirs. It describes different types of dams based on purpose, including storage dams, detention dams, diversion dams, coffer dams, and debris dams. It also discusses dam components and selection of suitable dam sites based on geological, technical, construction, and economic factors. The document further describes reservoirs and their types, as well as various geophysical studies used in engineering geology, including gravity, magnetic, seismic, radiometric, geothermal, and grouting methods.

1. ENGINEERING GEOLOGY OF DAMS
AND RESERVIORS
Presented by:
Dr.A.V.Deshpande
Department of Civil Engineering
SANJIVANI COLLEGE OF ENGINEERING
KOPARGAON

2. Types of Dams:
Based on purpose
1. Storage Dam Or Impounding Dam
2. Detention Dam
3. Diversion Dam
4. Coffer Dam
5. Debris Dam

3. 1. STORAGE DAM:
• It is constructed to create a reservoir to store water during
periods when there is huge flow in the river (in excess of
demand) for utilization later during periods of low flow.
• Water stored in the reservoir is used for irrigation, power
generation, water supply etc.

4. 2. DETENTION DAM:
• It is primarily constructed to temporarily detain all or part of the
flood water in a river and to gradually release the stored water
later at controlled rates
• So that the entire region on the downstream side of the dam is
protected from possible damage due to floods.
• It may also be used as a storage dam.

5. 3. DIVERSION DAM:
• It is constructed to divert part of or all the water from a river into
a conduit or a channel.
• For diverting water from a river into an irrigation canal, mostly a
diversion weir is constructed across the river

6. 4. COFFER DAM:
• It is a temporary dam constructed to exclude water from a
specific area.
• It is constructed on the u/s side of the site where a dam is to
be constructed so that the site is dry.
• In this case, it behaves like a diversion dam.

7. 5. DEBRIS DAM:
• It is constructed to catch and retain debris flowing in a river.

8. Based On Structural Behaviour
• Gravity Dam
• Arch Dam
• Buttress Dam
• Embankment Dam

11. A typical dam has following parts –
• Crest – The top of dam. In some cases, this provides a roadway
or walk way.
• Parapet walls – Low protective walls on the either side of the
road way on the crest.
• Abutments – The valley slopes on the either side of dam wall
to which it is keyed.
• Free board – The space between the highest level of water in
the reservoir and crest of the dam.

12. •
• Heel – The upstream portion of the dam in contact with the river
bed or foundations.
• Toe – The downstream portion of the dam wall for the discharge
of surplus water from the reservoir.
Spillway – The passage in the dam wall for the discharge of
surplus of water from the reservoir.
• Gallery – Level or gently sloping tunnel like passage transverse
or longitudinal within the dam wall with drains in the floor for
seepage water

13. SELECTION OF DAM SITE:
Selection of site – The selection of dam site across a river is to
impound water behind the dam. Following points are required
that –
Topographically, a place which is most suitable for the purpose is
selected. Ideally it should be narrow or a small valley with
enough catchment areas available behind so that when a dam is
placed there it would be easily store a calculated volume of
water in reservoir created upstream.
Technically, the site should be as sound as possible, strong,
impermeable and stable. Strong rocks for design, impermeable
for inventory of stored water and stability with references to
seismic failures.

15. • Constructionally, the site should not be far from deposits of
materials which would be required for construction.
• Economically, the benefits arising out of a dam is proposed to
be placed at a particular site should be realistic and justified in
terms of land irrigated , power generated and water stored i/c
floods averted.

17. • Geological investigations –
Following geological characters of the area should be
investigated for particular site selected for dam – Geology of
area comprising of main topographical features, natural
drainage patterns, general characters and structures of rock
formations, the trend and type of weathering and erosion of
area.

18. • Geology of site i.e. types of rocks of the area where dam will be
built, properties of rocks i.e. chemical composition, texture and
hardness of rocks, porosity and permeability of rocks.
• Structural features of the rock i.e. dip, strikes, outcrop etc.
Structural defect of rocks i.e. folds, fissures, faults etc.
• Crushing and shearing strength of rocks, extent of weathering of
rocks.
• Thickness of the bedding planes.
• Zones of fractures and weaknesses.
• Water table in the area

19. • The ideal foundation should be built over a uniform formation.
• The underlying rocks should be strong enough to bear weight
of dam and to withstand resultant thrust of pressure of the
impounded water and weight of dam itself.

22. RESERVIOR:
• A reservoir is a storage space for fluids. These fluids
may be water or gas.
• A reservoir usually means an
enlarged natural or artificial lake, storage
pond or impoundment created using a dam or lock to
store water.
• Reservoirs can be created by controlling a stream that
drains an existing body of water.
• They can also be constructed in river valleys using a
dam.

24. TYPES BASED ON PURPOSE:
Storage reservoirs:
• These are designed to increase downstream river
discharge during the dry season.
• Accordingly a portion of the rainy season flood water
mass is stored behind the dam and then released more
or less uniformly during the duration of the dry season
to provide a reliable and adequate year round water
supply for downstream users
(i.e. hydroelectric power plants, irrigation, municipal
water supply, navigation).

26. Flood control reservoirs
• These are designed to decrease the magnitude of the
peak flood discharge during the rainy season in order
to protect downstream areas from flood damage.
• They fill rapidly during the rainy season.
• Once the flood wave has passed, the stored water is
released.
• Water level and surface area experience a large annual
fluctuation.

28. Multi purpose reservior:
• Multipurpose reservoirs may be managed to balance some or all
of the following activities:
• Water supply
• Flood control
• Soil erosion
• Environmental management
• Hydroelectric power generation
• Navigation
• Irrigation

30. GEOPHYSICAL STUDIES
•
physical properties
Gravity and magnetic methods
rocks,of
susceptibility, and are very useful to field geologists
can be directly related to
i.e. the density and the
and
•
geophysicists in the mapping and identification of various rock
types.
They are also used for the detection of minerals with large
contrast in density and susceptibility compared to country rock.

32. Gravity method:
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Gravity surveying measures variations in the Earth’s
gravitational field caused by differences in the density of sub-
surface rocks.
Gravity methods have been used most extensively in the search
for oil and gas, particularly in the twentieth century.
Hydrocarbon exploration
Regional geological studies
Isostatic compensation determination
Exploration for, and mass estimation of, mineral deposits
Detection of sub-surface cavities (microgravity)

33. •
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Location of buried rock-valleys
ƒDetermination of glacier thickness
Tidal oscillations
Archaeogeophysics (micro-gravity)
Shape of the earths (geodesy)
Military (especially for missile trajectories)
Monitoring volcanoes.

36. Magnetic method:
• The magnetic method is a very popular and inexpensive
approach for near-surface metal detection.
• Engineering and environmental site characterization projects
often begin with a magnetometer survey as a means of rapidly
providing a layer of information on where utilities and other
buried concerns are located

37. Common uses of magnetometers include:
• Locating buried tanks and drums
• Fault studies
• Mineral exploration
• Geothermal exploration
• Mapping buried utilities, pipelines
• Buried foundations, fire pits for archaeological studies

38. Siesmic method:
•
•
Seismic techniques are commonly used to determine site geology,
stratigraphy, and rock quality.
These techniques provide detailed information about subsurface
layering and rock geo mechanical properties using seismic
•
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acoustical waves.
Reflection and Refraction are the most commonly used seismic
techniques.
These methods determine geological structure and rock velocities
by either refracting or reflecting waves off boundaries between
rock units with different seismic velocities or impedance.

39. • Seismology is the scientific study of earthquakes and the
propagation of elastic waves through the Earth or through other
planet-like bodies.
• The field also includes studies of earthquake environmental
effects, such as tsunamis as well as diverse seismic sources such
•
as volcanic, tectonic, oceanic, atmospheric, and artificial
processes (such as explosions).
A related field that uses geology to infer information regarding
past earthquakes is paleo seismology.

41. Radiometric method:
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The radiometric method is a geophysical process used to estimate
concentrations of the radio elements potassium, uranium and
thorium by measuring the gamma-rays which the radioactive
isotopes of these elements emit during radioactive decay.
Airborne gamma-ray spectrometric surveys estimate the
concentrations of the radio elements at the Earth's surface by
measuring the gamma radiation above the ground from low-flying
aircraft or helicopters.

43. Geothermal Method:
• Geothermal resource exploration, development, and production
draw on the techniques of both the mining and oil/gas industries.
• The geologic setting of geothermal resources is similar to
•
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deposits of metal ores, and geothermal systems are thought to be
the modern equivalent of metal ore-forming systems.
Hence, exploration draws most heavily on the techniques of the
mining industry.
Development of the resource and its production as hot fluid uses
the techniques of the oil/gas industry with modifications because
of the high temperatures and the much higher flow rates needed
for economic production.

44. GROUTING:
• Grout is a particularly fluid form of concrete used to fill gaps. It
is used in construction to embed rebar's in masonry walls,
•
•
connect sections of pre-cast concrete, fill voids, and seal joints
such as those between tiles.
Grout is generally a mixture of water, cement, sand, often color
tint, and sometimes fine gravel (if it is being used to fill large
spaces such as the cores of concrete blocks).
Finer particle sizes let the grout penetrate more deeply into a
fissure.

45. • Portland cement is the most common cementing agent in grout.
Portland cement-based grouts come in different varieties depending
on the particle size of the ground clinker used to make the cement,
with a standard size of around 15microns, microfine at around 6–10
microns.

46. Grout varieties include tiling grout, non-shrink grout, structural
grout.
• Tiling grout is often used to fill the spaces between tiles or
mosaics, and to secure tile to its base.
• Tiling grout is also cement-based, and comes in sanded.
• The sanded variety contains finely ground silica sand.
• Unsanded is finer and produces a non-gritty final surface.

47. • Non-shrink grout is used beneath metal bearing plates to ensure
a consistent bearing surface between the plate and its substrate.
• Often used as a transfer medium between load-bearing
members.

48. • Structural grout is often used in reinforced masonry to fill
voids in masonry housing reinforcing steel, securing the steel
in place and bonding it to the masonry.

49. IMPROVEMENT OF GROUTING AT SITES:
Some of these areas of expertise include:
1. Permeation
2. Jet Grouting
3. Hot Bitumen Grouting

50. PERMEATION GROUTING:
• Permeation Grouting consists of injecting grout under
•
controlled, low pressure in order to permeate the strata without
causing fracturing.
It can be applied in both soil and rock.

52. JET GROUTING
• Jet Grouting creates in-situ columns of grouted soil using very
high pressure grout injection.
• Grouting is performed by pumping high velocity jets of grout
(or sometimes grout and air or grout, water and air) through
the side of a grout monitor, attached at the end of the drill
string.

54. HOT BITUMEN GROUTING:
• Hot Bitumen Grouting is a special type of grouting where
melted bitumen is used as grouting material.
• The major feature of hot bitumen grout is its temperature
dependent viscosity. The bitumen is first preheated up to
approximately 200° Celsius.

56. TUNNELING:
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• A tunnel is an underground or underwater passageway, dug
through the surrounding soil/earth/rock and enclosed except for
entrance and exit, commonly at each end.
A pipeline is not a tunnel, though some recent tunnels have used
immersed tube construction techniques rather than traditional
tunnel boring methods.
A tunnel may be for foot or vehicular road traffic, for rail traffic,
or for a canal.