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ã ú â ûåöèâãèüøø

4 October , 2005 Graduate Seminar Briefings- ÷úâôüééûúüõúüîã úúüøø- úåõåéüúúâèã ú ô üééûúúüøø

âé+  âùôøâ âûã ú+  åéüúúâèã úúüøø (âèöú)

ååõ ú+  üøøéüúöèã úÿ ã  ú (ýâøûøèûâ /

ûõúùôø)

+  øúèúöè éèÿõ÷è ã úâèöúâå  è

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1. Dam Geology

2. åöèâã úúüøø

3. Water Resources Development

 ² åèâÿóú ú 4.  åèâã úâèöú5.  ø âèö ú6. å÷â â ûã ú

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DAMS

Dam Type Classification

1. Based on Purposes  / éúâöéõüèåâëèú. Storage or Impounding Dam

+ Hydro-electric power 

+ Irrigation

+ Water supply

.. Industry and domestic supply

+ Multiple or multipurpose dam

. Regulating or Detention Dam+ Flood regulation dam

+ Artificial recharge reservoir 

+ Irrigation regulating dam

2. Based on Construction Materials2.1 Gravity Dam

-  û Rock foundation and wide shallow valley öèèõâèü úéúúâ Aggregate supplies öèâ- Crest length > 5 H

- Cu 124 - 155 lbf/in2 (0.855 ± 1.07 MN/m2)

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- Base width = 2/3 H

- Triangular in cross-section úâôé üõúââè ÷õüôåúâöèõ  õâûûü ú pre-stressed gravity dam  õöõö  èã úõâ û úñúâ

2 .2  Buttress Dam

Strong foundation rock (2.14 - 3.22 MN/m2)

2 .3 Arch Dam

ã ú åè üâø+  Thick Arch Dam

. W/H = 3 - 5   úø ü úã úø ãèè(strong

abutments : strength+

3.22 MN/m2)

+  Thin Arch Dam

. Crest cord / H < 3

. Strong abutments(5.35 ± 7.49 MN/m2)

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2.4 Dome Dam/ Cupola Dam

ã ú ü åèâø å åèø  èúúúúö  è. Sound foundation and abutments

2.5 Multiple Arch- Buttress Dam

ã úýè Arch dam & Buttress dam

2.6 Embankment Dam

. Earth fills soft floors. Rock fills

. Impounding depth > 30 m.

RESERVOIR

DamS

ite GeologyConsider the following items :

.. Foundation

.. Reservoir Watertightness

.. Construction Materials

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Sele ction of Re ser  voir   Si te s

âôòâåõâèèèâ ûú  õèú  (i) Storage potential / âÿúââ ûââú .. Topography of the reservoir basin

(ii) Hydrogeological regime of the catchment --- >

Precipitation

(iii) Environmental constrainsts

Geological Criteria. Reservoir Watertightness

. Seepage --- > Permeable foundation

. Leakage

.. â  ìýúøè Residual soils / weathered zones

..    ýú transported soils (buried channels , etc.)

..    ýúøè èåâ / old mine workings

..    ýúøè faults , joints , bedding

..    ýúøè caves , solution channels , soluble rock basin

(karstic features)

. Reservoir side instability after impounding ââõâÿèø

 ãèþ èãûèâ ûú   ââââ û

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. Construction Materials

èõâè ø éë úèúâèã ú öè  âèâè

 ëúõãèõéã   úâ ûëúõãèã úø éè ë úClay core , Riprap ,

Blanket /liners , Aggregates , Bulk fills , etc. (âéèõâè)

. Dam Foundation

Dam Site :

.. Dam site geology (geol. mapping

+ Outcrop inspection

+ Excavation / pitting , etc.

+ Groundwater conditions

+  Site geology maps

+ Bore hole Sections

+  Rock head relations and weathering profiles

Structural Data

.. Rock / Soil typs Classifications

.. Rock origins

+ Weathering profiles

.. Mass permeability (K) and abutment stability

.. Bedrock conditions

.. Initial groundwater regimes (for potential leakage assessment)

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+ Use BH. Data to determine localized water pressure

(pore pressure) and to install piezometers

.. Permeability along the FLANKS and dam site.

.. Buried channels --- > determined by soft ground drilling in

combination with seismic surveys.

.. Deformability of rock and concrete (for concrete dam)

+ E concrete vs. E rock éöèåâåèâ ú ÿ üèâ údifferential deformation

.. Geological cross-sections --- > õèãú üãè BH-logs

Reservoir Feasibility:

åãèèâ ûú  âôò úâÿéôõèú   ;-.. Watertightness

.. Dam foundation

.. Construction materials

.. Stability of valley sides (reservoir sides)

.. Reservoir induced seismicity

.. Siltation --- > silt traps

.. Pollution+ Mineral deposits --- > waste mine (abandon mines)

+ Organic deposits -- > peat deposit

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Reservoir Location :

âåõâöúèø ö  èã ú ÿéôéââôò  2  üâ(i) Availability of water 

- Hydro-electricity

- Irrigation- Water supply

- Regulation

(ii) Topography

- Cost

- Volume of water impounded

(iii) WatertightnessSeepage / Leakage â  ìéâã úâõã   úõ øè õâ

a) Through dam and dam foundation

b) Through reservoir flanks and bedrock conditions

+ Lithologies

. Structures

. Geomorphology (buried channels , etc.)

. Artificial excavation (mining)

. Leakage through soluble rocks (caves , solution tunnels,

fracture system)

c) Through reservoir basin -- >

. Blanket breakage

. Geological defects

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