Hana shehu ZEKIRIJA IDRIZI Introduction Dams and their purpose The importance of Dams as structures water supply flood control irrigation navigation sedimentation control ID: 1019431
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1. Stability analysis of embankment damsHana shehuZEKIRIJA IDRIZI
2. Introduction – Dams and their purpose The importance of Dams as structureswater supply,flood control, irrigation, navigation,sedimentation control, andhydropower.The Design and Construction “trial and error” vs. “computations”THE SINGLE PURPOSE DAMS
3. The history of building dams“Sadd-el-Kafara” Dam – EgyptDams of the mining industries – Harz Mountains - GermanyOld method of ConstructionNew method of Construction11m high rockfill dam – earth core2600 BC (flood control)Destroyed during construction - overtopping
4. Water resources and dams in KosovaKosova has 5 artificial lakes which are the main form of water supply:BATLLAVA BADOVCI RADONIQI UJMANI (Gazivoda) PËRLEPNICA“UJMAN” lake and embankment dam Height:107.5 meters
5. Embankment dams – types and characteristicsEmbankment dams – Earth fill and Earth - Rockfill materials75% of all world damsThe prevailing of embankments in the modern dam construction is mainly because of:The climate, topography, and geology conditions Construction materials are principally supplied near the dam siteEconomical advantage The development of rock and soil mechanicsThe advanced construction equipments (heavy vibrating roller, hydraulic vibrating plate, laser-oriented gradall, etc.)
6. STABILITY ANALYSIS OF EMBANKMENT DAMSThe stability of dams and their foundation – different conditions and load cases and combinationsConstructionExploitation period. Loads can be:Static loads (dead load and impounding)Dynamic loads (seismic forces)LOADS ON EMBANKMENT DAMS
7. STATIC LOADSDEAD LOADDeformation of the dam body – dam zoning and material propertiesDead load – during constructionDam construction (individual layers) - settlements of the previous dumped layers and of the foundation.Pore water pressure - all fine grained materials, construction materials, the foundation. Kinda Dam – settlements after constructionMeasured – 130cm and Computed – 180 cm
8. Static loadsIMPOUNDINGThe stress and strain conditions - change under the effect of the water load. Change is in principle different for dams with an internal sealing and dams with a face sealing. This follows from the different locations of the resultant of the hydrostatic pressure.Kinda Dam - Computed lines of equal horizontal displacements after impounding to 0.7H
9. Failure of embankment damsFailures of embankment dams can generally be grouped into three classifications:
10. Slope stability analysisSlope stability analysis – practical importanceStability is determined by the balance of shear stress and shear strength. “If the forces available to resist movement are greater than the forces driving movement, the slope is considered stable.”Factor of safety Different slope sliding surfaces“To determine the surface of sliding, with the smallest factor of safety - we need to examine quite a number of surfaces of sliding in different positions”
11. METHODS OF STABILITY ANALYSISDevelopment of methods for determination of the static stability - make possible the design of a safe and economical dam structure. The methods for calculating the stability of embankment dams are divided into:
12. Limit Equilibrium methodsMETHODS OF SLICES Swedish Slip Circle Method of AnalysisOldest method - This method gives lower values for the safety factor, as compared to the more accurate methods by 5–20%. Ordinary Method of Slices Modified Bishop’s Method of Analysis suitable for programming, more accurate than the Swedish one, while the disregard of the safety factor does not exceed 7%. Lorimar’s Method of Analysis Spencer’s Method of Analysis
13. Limit Equilibrium MethodsSimplicity and accuracy. Must search for critical surface by using geometry. The method of slices is based purely on the principles of statics; the summation of moments, vertical and horizontal forcesIt requires only a simple Mohr - Coulomb soil model. It cannot compute displacement. It cannot model progressive failure. Finite Element Method Computer performance has improved application of FE in geotechnical analysis. The critical surface is automatically fond out by various software’s. Better visualizes the deformation of soil in place. It must have complete stress- strain model for soil. It can compute displacement. It can model progressive failure.
14. ConclusionsDams - high economic and political importance, critical role in agriculture, development of urban and rural areas, water supply, generation of hydroelectric energy, control and regulation of water current velocity. Slope stability analysis is very important to ascertain the stability of the structure. It depends on its geometry, its components, materials, properties of each component and the forces to which it is subjected. A failure of earth dam is attributed to the following: hydraulic failure, seepage failure, piping through dam body and structural failure due to earthquake.
15. conclusionsThere are several applicable methodologies that have been put forward for analyzing the overall stability of a dam, from classical methods to modern ones;The infinite slope model is more suitable and convenient for the surficial slope stability analysisThe limit equilibrium models are professional for the circular slip surface analysis in the deep slope and could provide a much higher accuracy but with much more complicated calculation process.
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