Irrigation Practical on visulation of flow lines

1. Experiment:07
Seepage through Earth Dam
K16CE-58 G.L
K16CE-48 A.G.L
K16CE-08
K16CE-09
K16CE-34
K16CE-46

2. Object: Visualize the position and shape of the
flow line in an Earth Dam
Seepage:
It is movement of water in soils. Seepage depends on
several factors , including permeability of soil and the pressure
gradient.

3. Types of Failure due to Seepage:
1. Failure by undermining

4. 2. Failure by direct uplift

5. Earth Dam :
Dams built up by compacting successive layers of
earth, using the most impervious materials to form a core and placing
more permeable substances on the upstream and downstream.

6. Seepage Failure of Earthen Dam
1. Piping through Foundation

7. 2.Piping through Earthen body

8. 3. Sloughing of Down Stream Toe

9. Apparatus : Permeability Tank
Description: The apparatus is a transparent-sided tank, mounted
on a steel-framed bench with worktop. The tank is clear so
students can see the flow patterns. The sides are plate glass to
resist abrasion from the permeable medium
Learning outcomes
• Determination of seepage beneath a structure
• Construction of flow nets and determination of coefficient of
permeability
• Flow under a sheet pile and determination of critical seepage
force at which ‘piping’ occurs
•Flow through an earth dam with and without a toe drain

10. • Drawdown in horizontal flow (simulation of ground water flow
into a river or well)
•Determination of uplift pressures on structures such as building
foundations
• General studies of seepage and drainage
• Flow through a porous medium (Darcy’s law)
Essential Services
Water supply:
Clean, cold water and drain
Space needed:
2.5 m x 1.5 m of solid, level floor

11. Operating Conditions
Operating Environment:
Laboratory
Storage Temprature Range:
–25°C to +55°C (when packed for transport)
Operating temperature range:
+5°C to +40°C

12. Operating Relative Humidity Range:
80% at temperatures < 31°C decreasing linearly to 50% at
40°C
Specifications
Nett dimensions and weight:
2450 mm x 700 mm x 1500 mm and 230 kg
Nominal Internal Tank Dimensions:
1800 mm or 1500 mm between mesh screens x 600 mm high x
180 mm width

13. Permeability Tank

14. Procedure:
A segment of a dam of trapezoidal cross section is formed from sand
in the tank so that the base of the dam is about 6 inches above the
bottom of tank. The upstream slope can generally be steeper than the
dls one and its toe should be approximately at the over flow outlet.
For current laboratory sands, a stable dam cross section will have an
upstream slope of approximately 1:3 to 2:3 and a dls slope of about
1:5 to 1 :4. The height of the dam should be 10 inches, the crest
width approximately 3 inches. The upstream water level should be
stabilized one inch below the dam crest; the dls level about 4 inches
above the bottom.

15. After the dam segment has been formed, water is first poured into the
dls pool. Only after it is full should the upstream pool be fitted. The
rate of fitting should be slow. Otherwise the dam segment can easily
collapse. When the upstream water level is stabilized, needles with
dye are inserted along the upstream slope (next to the transparent side
of the tank), the first being fixed immediately at the water surface
.

16. VIDEO

17. Hydrus Standard Software Results