Stability Analysis of Mula Dam , Types of Dams

1. STABILITY ANALYSIS OFSTABILITY ANALYSIS OF
MULA DAMMULA DAM
(EARTHEN DAM)(EARTHEN DAM)
By
Prof.M.PWAGH

2. IntroductionIntroduction
 Dams may be defined as an obstructionDams may be defined as an obstruction
or a barrier built across a stream or aor a barrier built across a stream or a
river.river.
 Purpose of Dam:Purpose of Dam:
1. Controlling Flood1. Controlling Flood
2. Irrigation2. Irrigation
3. Water Supply3. Water Supply
4. Generation of Electricity (Hydro Power)4. Generation of Electricity (Hydro Power)
5. Used for fish Culture5. Used for fish Culture
6. Diversion of Water6. Diversion of Water
7.7. 6 MW Hydro- power generation6 MW Hydro- power generation
(Under(Under
Construction)Construction)

3. Objective of ProjectObjective of Project
 To study the salient features of MulaTo study the salient features of Mula
DamDam
 To Carry out Stability Analysis of MulaTo Carry out Stability Analysis of Mula
DamDam
 To Study Hydro Electric Power PlantTo Study Hydro Electric Power Plant
 Design of SpillwayDesign of Spillway
 To Study Instrumentation in DamsTo Study Instrumentation in Dams

4. Types of DamTypes of Dam
 Dams are of the following types:Dams are of the following types:
 1. Embankment Dam1. Embankment Dam
 2. Gravity Dam2. Gravity Dam
 3. Arch Dam3. Arch Dam

5. Earthen DamEarthen Dam
 Earthen Dam are classified as:Earthen Dam are classified as:
 Homogenous Embankment typeHomogenous Embankment type
 Zoned Embankment type: It consistsZoned Embankment type: It consists
of more than one type of material i.e.of more than one type of material i.e.
the central impervious core is flankedthe central impervious core is flanked
by zones of materials considerablyby zones of materials considerably
more pervious.more pervious.
 Diaphragm typeDiaphragm type

6. Methods of ConstructionMethods of Construction
 There are two methods of constructionThere are two methods of construction
of Earthen dam:of Earthen dam:
1.1. Hydraulic – fill methodHydraulic – fill method: In this: In this
method excavation & transportation ofmethod excavation & transportation of
soils are done by using water.soils are done by using water.
2.2. Rolled – fill methodRolled – fill method: In this, material: In this, material
is transported from the borrow pits tois transported from the borrow pits to
dam site by trucks & scrapers anddam site by trucks & scrapers and
spread to form layers of 15 to 45 cmspread to form layers of 15 to 45 cm
thickness.thickness.

7. MULA Project - IntroductionMULA Project - Introduction
 This Project was considered in 1877 for aThis Project was considered in 1877 for a
storage project for irrigation for Rahuri &storage project for irrigation for Rahuri &
Newasa TahsilsNewasa Tahsils..
 The river Mula rises in Western Ghats ofThe river Mula rises in Western Ghats of
Harischandragad in ranges of SahyadriHarischandragad in ranges of Sahyadri
 This is one of the major projects constructed onThis is one of the major projects constructed on
Mula river, a tributary of River Godavari, atMula river, a tributary of River Godavari, at
Baregaon Nandur, Tal: Rahuri, Dist:Baregaon Nandur, Tal: Rahuri, Dist:
Ahmednagar.Ahmednagar.
 The Catchment area is elongated to leaf shapeThe Catchment area is elongated to leaf shape
and has total area of 2274 sq.kmand has total area of 2274 sq.km

8. Review of Mula ProjectReview of Mula Project
 Mula Dam is a Earthen Dam with GatedMula Dam is a Earthen Dam with Gated
SpillwaySpillway..
 The length of dam is 2856 M.The length of dam is 2856 M.
 The Maximum Height of Dam is 48.13 M.The Maximum Height of Dam is 48.13 M.
 Spillway is Masonry type having total lengthSpillway is Masonry type having total length
298.70 M.298.70 M.
 The gates are Radial type & are 11 nos.The gates are Radial type & are 11 nos.
 The designed discharge is 5947.20 Cumecs.The designed discharge is 5947.20 Cumecs.

9. Method of AnalysisMethod of Analysis
 The analysis of dam is done by SwedishThe analysis of dam is done by Swedish
circle Method for upstream andcircle Method for upstream and
downstream slope.downstream slope.
 Phreatic line is decided.Phreatic line is decided.
 U/S slope is checked for suddenU/S slope is checked for sudden
drawdown condition.drawdown condition.
 D/S slope is checked for steady seepageD/S slope is checked for steady seepage
condition.condition.

10. DesignDesign
 Factor of safety = resisting forces /Factor of safety = resisting forces /
Actuating forcesActuating forces
 Factor of safety for U/S = 1.72 > 1.5Factor of safety for U/S = 1.72 > 1.5
 Factor of safety for D/S = 1.8 > 1.5Factor of safety for D/S = 1.8 > 1.5

11. SpillwaySpillway
 Spillway is structure constructed at a damSpillway is structure constructed at a dam
site for effectively dispersing of surplussite for effectively dispersing of surplus
water from upstream to downstream.water from upstream to downstream.
 LocationLocation:- a spillway may be either within:- a spillway may be either within
the body of dam or at one end of it orthe body of dam or at one end of it or
entirely away from it.entirely away from it.
 Spillway of Mula dam is located at leftSpillway of Mula dam is located at left
saddle.saddle.
 It is Ogee spillway with 11 radial gates.It is Ogee spillway with 11 radial gates.

12. Types of SpillwayTypes of Spillway
 Classification based on function:Classification based on function:
 1. Main or Service Spillway.1. Main or Service Spillway.
 2. Auxillary Spillway2. Auxillary Spillway
 3. Emergency Spillway3. Emergency Spillway
 Classification based on Flow through Spillway:Classification based on Flow through Spillway:
 1. Gated /Controlled Spillway1. Gated /Controlled Spillway
 2. Ungated / Uncontrolled Spillway.2. Ungated / Uncontrolled Spillway.

13. Types of SpillwayTypes of Spillway
 Classification based on prominent featuresClassification based on prominent features
pertaining:pertaining:
 Free overfall / Straight drop SpillwayFree overfall / Straight drop Spillway
 Chute / Open / Trough SpillwayChute / Open / Trough Spillway
 Side Channel SpillwaySide Channel Spillway
 Shaft / Morning glory SpillwayShaft / Morning glory Spillway
 Conduct / Tunnel SpillwayConduct / Tunnel Spillway
 Siphon SpillwaySiphon Spillway
 Overflow or Ogee SpillwayOverflow or Ogee Spillway

14. Forces acting on SpillwayForces acting on Spillway
 Water PressureWater Pressure
 Uplift pressureUplift pressure
 Pressure due to Earthquake forcesPressure due to Earthquake forces
 Silt PressureSilt Pressure
 Wave PressureWave Pressure
 Ice PressureIce Pressure
 Self WeightSelf Weight

15. Failure of SpillwayFailure of Spillway
 By Overturning about the toeBy Overturning about the toe
 By CrushingBy Crushing
 By development of TensionBy development of Tension
 By Shear FailureBy Shear Failure

16. THANK YOUTHANK YOU