Lesson 7 - nptel

More documents

Recommendations

Info

The filter layers should be extended upto the outer slopes of the embankment so as to drain out the collected water. These filter layers should not be connected with inclined or vertical filters. A minimum space of 2.0 m or more, should be kept between the face of inclined/vertical filter and downstream intermediate filter. The material of the filter layers should be protected at exposed faces as shown in Figure 38. Details are shown in Figure 39. Version 2 CE IIT, Kharagpur
Rock Toe The principal function of the rock toe is to provide drainage. It also protects the lower part of the downstream slope of an earth dam from tail water erosion. Rock available from compulsory excavation may be used in construction of the rock toe. Where this is not possible and transportation of rock is prohibitively costly, conventional pitching should be used for protecting the downstream toe of the dam. The top level of the rock toe/pitching should be kept above the maximum tail water level (TWL). In the reach where the ground level at the dam toe is above the maximum tail water level, only conventional pitching should be adopted. The top of such pitching should be kept 1.0 m above the top of horizontal filter, or stripped level, whichever is higher. A zone of coarse filter should be introduced between the rockfill/ pitching and the fine filter. A combination of partial rock toe and pitching may also be considered to effect economy. Details of rock toe/pitching protection and toe drains are illustrated for various combination of Tail Water Level (TWL) and stripped Ground Level (SGL). 1. Rock toe when TWL is higher than SGL (Figure 40) 2. Pitching when TWL is higher than SGL (Figure 41) 3. Rock toe + pitching when TWL is higher than rock toe (Figure 42) 4. Pitching when SGL is above TWL (Figure 43) 5. Pitching and lined toe drain (Figure 44) Version 2 CE IIT, Kharagpur
Page 1 and 2: Module 4 Hydraulic Structures for F
Page 3 and 4: Instructional objectives On complet
Page 5 and 6: Version 2 CE IIT, Kharagpur
Page 7 and 8: An embankment dam is not as impervi
Page 9 and 10: Here, too it may be observed that t
Page 11 and 12: Though this is entirely satisfactor
Page 13 and 14: Another layout of the combination o
Page 15 and 16: Both the spillway section and the p
Page 17 and 18: The example of Beas Dam at Pong (Fi
Page 19 and 20: Another example is given in Figure
Page 21 and 22: spillway. Overtopping may also be c
Page 23 and 24: 2. Conduit leakage: This is caused
Page 25 and 26: drops to zero, which means the soil
Page 27 and 28: Version 2 CE IIT, Kharagpur
Page 29 and 30: 1. Safety against hydraulic failure
Page 31 and 32: 2. Safety against seepage failures
Page 33 and 34: for resisting the piping action. Th
Page 35 and 36: Inclined/Vertical Filter Inclined o
Page 37: Transition Zones and Transition Fil
Page 41 and 42: Toe Drain Toe drain is provided at
Page 43 and 44: Grout Curtain Grout Curtain in Perv
Page 45 and 46: Relief Wells Relief wells are an im
Page 47 and 48: As may be observed from Figure 48,
Page 49 and 50: Quantity of seepage flow An embankm
Page 51 and 52: The slope stability methods general
Page 53 and 54: The above critical conditions are e
Page 55 and 56: Earthquake Condition In the regions
Page 57 and 58: In some rivers, the floods may be s
Page 59 and 60: To reduce the hydrostatic pressure
Page 61 and 62: Movements Measurement of movements
Page 63 and 64: Horizontal movement gauges Cross-Ar
Page 65: Electrical Piezometers: Electrical

Lesson 7 - nptel

Create successful ePaper yourself

Delete template?

Save as template?