Control Seepage Thought Earth Dams

Control seepage through earth dam

AHMED MANSOR Control seepage through earth dams
Control Seepage Thought
Earth Dams
Ahmed Mansor
Supervision
Dr.Samar Mohamed
Eng.Ahmed Fathey

ACKNOWLEDGMENTS:
Thank Everyone add to me something positive in my life
Thank you :
Dr.Samar Mohamed
Eng. Ahmed Fathey
Ahmed Mansor
1

ABSTRACT:
This study was competent studied earth dams and species and its history
and the factors influencing them and the other part of a study of the most
important risks that affect earth dams (seepage through earth dams) and
how to calculate the leak and methods of their account and types the
seepage and forms of cost and what are the ways process is treated with
filters.
2

TABLE OF CONTENTS
ACKNOWLEDGMENTS 1
ABSTRACT 2
NOMENCLATURE 5
CHAPTER 1
1. INTRODUCTION TO SEEPAGE THROGH EARTH DAM 6
1.1What the earth dam? 6
1.2Type of earth dam 6
1.3 Choose depends on the type of dam 8
1.4 History 8
1.5 Requirements of Safety 10
CHAPTER 2
2.METHODS CALCULATION SEEPAGE THROGH EARTH
DAM
11
2.1 Calculation of seepage through an earth dam
resting on an impervious base
11
Dupuit`s Solutions 11
Shcafferank`s Solutions for α 30° 12
Gasagrande`s Solutions for α 30° 13
CHAPTER 3
3. ENTRANCE, DISCHARGE, AND TRANSFARE
CONDITIONSOF LINE OF SEEPAGE
15
3.1. Type of Discharge and Transfer 15
3.2. Drawi g etwork of da ’s dirt ru off 16
3

CHAPTER 4
4.SIMULATE THE PRESSURE ON THE EARTH DAM USING SAP 2000 PROGRAM 17 18
4.1Design The Dam 18
4-2Analysis in two Cases 22
5.DESIGN FILTER TO CONTROLED THE SPAAGE IN EARTH DAM
5.1 Use filter 23
5.2 Terms of material selection, which makes them a Filter 23
5.3 Terms various specifications of the candidate 25
6.CONCLUSIONS AND DISCSSION 26
7.REFERENCES 27
4
CAHPTER 5

Nomenclature:
Quantity Units Name unit
q ( flow ) ms Meter per second
Distances m Meter
F (force ) t Ton
Moment t.m Ton*meter
Grain size m.m Mile meter
5

CHAPTER 1
INTRODUCTION TO SEEPAGE THROUGH EARTH DAMS
1.1 What the earth dams?
The earthworks to order water and store it or to protect the site during the
implementation of the foundations work. Earth dams made of earth and
therefore different levels of water in front of and behind the dam is causing
leakage of water from the dam through the dam.
1.2 Types of earth dams
 Homogeneous dam with internal drainage on impervious foundations.
 Central core dam on impervious foundations.
 Inclined core dam on impervious foundations.
 Homogeneous dam with internal drainage on pervious foundations.
 Central core dam on pervious foundations.
 Dam with upstream impervious zone on pervious foundations.
 Other type dams :
1- Concrete.
2- Roller Compacted concrete.
3- Debris flows.
6

Figure 1-1. Types of dam sections
Figure 1-2 Roller compacted concrete
7

Figure 1-3 Debris flows dam
1-3 Choose depends on the type of dam
 Materials available
The transfer of materials that are not available from the remote location
is too expensive in addition to the cost of materials.
 Land quality and soil, which will be held by the dam
So as to protect the dam from landing and that the soil and ground
borne.
 Study Zone
Are basic materials are available?
Are the rocks are available?
1-4 History
 Levees or dikes have protected lands since primitive times and earth
dam have been used for the storage water for human need and
protection for more than 2000 years. In the year 500 B.C (1)
. An earth
dam containing nearly 20 million cu(2)
. Yd (3)
. Of earth was completed in
Ceylon (Now Sri lanka).
Early dams and levees were constructed simply by heaping earthen
materials across an area to be blocked, human traffic often producing all
the compacting effort. Many of the early efforts were washed out by
overtopping , under seepage , or other destructive forces , but eventually
standards of practice emerged that can be called " rules of thumb "
These practices often had no real basis , except that something had
worked at a number of locations ; hence it might work elsewhere.
Even into the twentieth century dams and levees were being designed
8

largely by empirical methods. Wegmann (1922) states:
The design of such work (earth dam) should not be based upon
mathematical calculations of equilibrium and safe pressure. As in the
case of masonry dam, but upon results found experience. Most of earth
dams constructed within the last century have had a large margin of
safety in resisting the water pressure , both as regards overturning and
sliding , and yet frightful disasters , such as the rapture of the Dale Dyke
and the Johnstown dam . Have resulted from the faults in designing
some details or from neglect in the construction of the work.
From about 1930 to the present time 1988, analytical and experimental
methods have had an increasingly important part in the design and
construction of earthwork. They will continue to play an important role in
the design of dams, but experience will also have a dominant place. As the
weaknesses of modern practices come to light in occasional failures new
standard will emerge. These standards will continue to improve because
they will be based on fundamental principles and broad experience.
Figure 1-4 Dale Dyke and the Johnstown dam
9

1-5 Requirements of Safety
 Their slopes must be stable under all conditions.
 Their foundations must not be overstressed.
 Safe against internal erosion and water forces and pressure.
 But 80% of the dams collapse because uncontrolled seepage.
10

CHAPTER 2
METHODS TO CALCULATION SPEEPAGE TROUGHT
EARTH DAMS
2-1 Calculation of seepage through an earth dam resting on an impervious
base:
 Dupuit`s Solutions
In figure (2-1) Earth dam in it a, b is phreatic surface or the uppermost
line, Amount of leakage through a unit of length is given Darc law:
(q = k i A), Hydraulic slop is i Expressed � =
∆ ℎ
�
.
Hence;
q = k
∆ ℎ
(y) (1) = k
∆ ℎ
(y)
∫ � � = ∫ � �
�
�
�
qL = � − �
q = � − � …….… (2- 1)
Equation 1 represents the equivalent cut phreatic surface.
The equation did not take into account the entrance and exit. Should also note
that if Hz = 0, pheaticline cut the surface layer impermeable.
Fig. 1-2: Dupuit`s Solutions for flow through earth dam
11

Phreatic line
Where:
H or h1: high upstream water.
He or h2: high downstream water.
L: length the x- axis under phreatic line.
X: length the x- axis.
K: coefficient of permeability.
 Shcafferank`s Solutions for α 30°
In this way is a Phreatic line and a father who goes back tilt at a distance
of 1 and leakage per unit length appointed by using the triangle D C B
As in figure (2-2):
Fig. (2-2): Shcafferank`s Solutions for flow through earth dam
 Shcafferank`s Solutions ( a , q ) :
q = Kh
ℎ
= K (a sin α) (tan α) (2-4)
Where:
q: flow rate.
K: coefficient of permeability.
a: downstream slope distance.
h : high upstream .
a =
�
∝
- √
�2
2∝
− √
�2
� 2∝
( 2-5 )
(2-2) (2-3)
12

where :
a : downstream slope distance .
L : Horizontal distance on the X axis .
H : high upstream .
 Gasagrande`s Solutions for α 30°
Explain that in practice the curve A B must start from the point A` As
in figure ( 2 -3 ) :
Fig (2-3) Gasagrande`s Solutions
 Gasagrande`s Solutions ( a , q )
q = kh
ℎ
= k a �� ∝ (2-6)
where:
q : flow rate .
k : Anisotropic .
h : high upstream .
a = S0 - √Sₒ −
H2
sin2∝
(2-7)
where :
H : high upstream .
S0 : is length the curve A`CB .
13

Fig (2-4) Gasagrande`s Solutions through earth dam .
14

CHAPTER 3
ENTRANCE, DISCHARGE, AND TRANSFARE
CONDITIONS OF LINE OF SEEPAGE
3-1 Type of Discharge and Transfer:
 When the leakage from the center of a free disposition (high
permeability coefficient) to the center of impermeability few labs called
this Entrance cond.
 When the leakage from the center of a few permeability to the center of
great permeability are called this discharge cond.
 When the leakage from the center of a few permeability to permeability
less is called transfer.
Fig (3-1) Entrance Cond
Fig (3-2) Discharge Cond
15

Fig ( 3-3 ) Transfer Cond
(3-2) Drawing network of dam’s dirt runoff
 Drawing the Phreatic line.
 ED: Head line, BA: Flow line.
 Head line at any point on the Flow line equal = 0.
 Drawing the Head line to Dam and cross point between the Head line
and Flow line it’s the start the equipotential line.
∆h =
ℎ
� ℎ
(3-1)
 Drawing the network of dam .
 Calculate The flow rate to the Dam ( q ) from equation :
q = k h
� ℎ
� ℎ
(3-2)
 But If they permeability coefficient between the X-axis and Y-axis flow
is calculated by the following law:
16

q = h
� ℎ
� ℎ
√� � (3-3)
Where:
∆h: high of pressure of flow channel.
h: total high of pressure of flow channel.
q: flow through earth dam.
Kx: permeability coefficient for X-axis.
Ky: permeability coefficient for Y-axis.
Fig (3-4) Steps the drawing the Net flow for Earth Dam
Fig (3-5) the Number of flow channels and Pressure channel
Fig (3-6) The constant of the permeability coefficient
17

CHAPTER 4
SIMULATE THE PRESSURE ON THE EARTH DAM
USING SAP 2000 PROGRAM
(4-1) Design The Dam:
Fig(4-1) Elevation Dam Fig(4-2) Isometric Dam
 The Dimensions on the Dam
Fig(4-3) Dimensions on the Elevation Dam
18


Fig (4-4) Dimensions on the Isometric Dam
 Simulate the force that affects the water from upstream the dam to one
ton per meter.
Fig (4-5) Simulate the force that affects the water from upstream the dam to
one ton per meter.
19

Fig (4-6) The Bending Moment Diagram from Force one Ton on the Dam
Fig (4-7) The Shear Force Diagram from Force one Ton on the Dam
20

 Simulate the force that affects the water from upstream the dam to one
ton per meter in (23) of length the Dam Body and from downstream one
ton per meter in (13) of length the Dam Body.
Fig (4-8) Simulate the force that affects the water from upstream the dam to one ton
per meter in (23) of length the Dam Body and from downstream one ton per meter in
(13) of length the Dam Body.
Fig (4-9) Bending Moment Diagram for the Case
21

Fig (4-10) Shear Force Diagram for the Case
(4-2) Analysis in two Cases:
 Max B.M.D and Max S.F.D in two Cases : in Table (4-1)
Case 1 Case 2
Max B.M.D Max S.F.D Max B.M.D Max S.F.D
17.62 8.08 17.28 7.77
Chart (4-1) Relationship between Case 1 and Case 2
22

CHAPTER 5
DESIGN FILTER TO CONTROLED THE SPAAGE IN
EARTH DAM
(5-1) Use of Filter:
 Filter uses a process to control the leakage through the earth dam. And
when the flow of water from the soil into the soil soft coarse, it causes
dangerous where the soil is soft soil is coarse. Over time, this process
hinders the blanks in coarse soils. In such a case you must use the filter to
prevent the soils.
(5-2) Terms of material selection, which makes them a Filter:
 The size of the blanks of a material Filter must be small enough for the
survival of larger grains in place.
 Material made by a Filter must be a high permeability to prevent the
formation of a large leak or hydrostatic pressure forces the Filter.
Depending on the mixing process Bertram substance research candidate
the following values:
� F
�85 S
≤ 4 to 5 (to satisfy condition 1) (5-1)
� 5 F
� 5 S
≥ 4 to 5 (to satisfy condition 2) (5-2)
Where:
D15 (F): diameter through which 15% of Filter materials will pass.
D15 (S): diameter through which 15% of soil to be protector will pass.
The equations (5-1) and (5-2) Select the size distribution of the soil used
as a Filter.
For example the dam in fig (5-1) Where the size distribution of the
granules is arranged a curve in fig (5-2) then determined the 5D85(s) ,
23

5D15(s) And it is located on the curve in Fig (5-2) Be a gradation of
granules suitable filter if it occurred in the shaded area in Fig (5-2)
Fig (5-1) Use of filter on earth dam
Fig (5-2) Determination of grin size distribution of soil filter
24

(5-3) Terms various specifications of the candidate:
 To avoid movement grained soil to be protected:
� 5 F
� 5 S
20 (5-3)
�5 F
�5 S
25 (5-4)
� 5 F
�85 S
5 (5-5)
 To avoid the leak forces high from filter:
� 5 F
� 5 S
4 (5-6)
 Material of filter should not be the size of grains crystallized more
than 3 inches (76.2mm) , (This is to avoid segregation in materials
in the filter)
 To avoid internal motion of the granules in the soft candidate must
not be more than passing sieve 200 for 5%.
 When using water leakage pipe assembly, the filter must take these
pipes to protect the soft-grained shelf to the inside of the tubes. And
to avoid movement martial Filter to drainage pipes should be the
availability of the following conditions:
�85 F
� ℎ
1.2 to 1.4 (5-7)
�85 F
ℎ �
1.0 to 1.2 (5-7)
25

CONCLUSION AND DISCUSSION
Discussion:
 In light of this study, we know that the earth dams have a history of a very
old and it was used in ancient purposes as important as agriculture, flood
protection, but the spread of these dams has not prevented it was
dangerous often because they are made without considering's prior and
not geometric laws was so the reason for its collapse and cause major
disasters and was the most important reasons for the collapse of earth
dams is the leakage that which is happening due to the heterogeneity of
the soil components of the bridge and not to control the flow inside the
soil components of the dam but with the development of science, there has
become a standard on which to base the dam of this type of dams and also
provides tools to control the leakage that occurs within them.
Conclusion:
 Through this study was reached important results, including the
simulation of the origin of earth dam program SAP 2000 in two cases,
when the first case when the acting force only come from upstream and
the second case when the forces acting on the body of the dam from the
upstream and Down Stream has resulted in the case two given strains over
the dam through moments and shear strength representation and expense
through the relationship diagrams to clarify the relationship and when you
design the filter to control seep through the dam became clear that the
design of the filter depends size granules from the experience of sieves to
determine the type of soil suitable for the manufacture of a filter and that
each candidate particular purpose depending on the properties, which is
designed for.
26

References
 R.F Craig (1974) , "Craig`s Soil Mechanics" , Formerly Department of
civil Engineering , University of Dundee UK .
 Cedergren, H.R. (1989) Seepage, Drainage and Flow Nets, 3rd
end, John
Wiley & Sons, New York.
 Harr, M.E. (1962 ) Groundwater and Seepage, McGraw-Hill, New York.
 Bishop, A.W. , Alpan , I., Bilght, G.E. and Donald , I.B. (1960) Factors
Controlling the strength of partly saturated cohesive soils, in proceedings
of the ASCE conference on shear strength of cohesive soils, Boulder, CO,
USA, ASCE , New York , pp 503-32 .
 Bishop, A.W Green, G.E., Garga, V.K., Andersen, A. and Brown J.D.
(1971) A new ring shear apparatus and its application to the measurement
of residual strength, Geotechnique, 21, 273-328
27

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Control Seepage Thought Earth Dams

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