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Laboratory Teaching Exercises
Index to Exercises
Exercise A - Seepage Underneath a Sheet Pile Wall
Exercise B - Seepage Through an Earth Dam
Exercise C - Draining Effect of a Tile Line
Exercise D - Draining Effect of an Open Trench
Exercise E - Uplift Pressure on Foundation of Structures
Exercise F - Changing Uplift Pressure by Changing Length of Flow Lines
Exercise G - Reduction of Uplift Pressure by Draining
Exercise H - Reduction of Lateral Thrust on a Retaining Wall by Draining
Exercise J - Quicksand
Exercise K - Stability of an Earth Dam
Exercise L - Well Draining
General Comments
The following set of experiments has been designed to demonstrate the most typical
situations that arise in dealing with water as it moves through a permeable medium.
The situations described are mostly "engineering" situations. In addition to the water
and the medium through which it moves, they usually involve some artificial, or
"engineering" element like a wall, a dam, a tile line etc. There are fourteen basic
experiments and two variants described. However, any number of other practical
investigations can be made which will add to general knowledge and enrich the
experience of the experimenter.
Several basic rules should be followed in order to obtain good results. First of all,
great care is needed in sealing the areas of contact between the membranes and the
tank walls. To achieve a well-sealed contact requires clean, sand-free tank walls and
membrane edges. Since the membrane will move downstream under the water
pressure, when a sealer is used it should be applied along the downstream side of
the contact area. The second important rule is to pour water into the tank slowly,
starting with the downstream pool. And finally, it should be remembered that it is
seldom successful to alter the experimental set-up after the contact areas have been
sealed and the tank filled with sand and water. Each change of location of a
membrane inside the tank usually requires the same amount of work and care as the
set-up of a new experiment.
A detailed step-by-step description of each operation is given in the set-up of
Exercise A. In the following teaching exercises detailed descriptions of the recurring
basic operations (dye injection, membrane sealing, etc) are not repeated.
