Purpose
The
purpose of this experiment was to determine the effect of dirt compaction on
the ability of dirt to hold water in a simulated levee.
I
became interested in this idea when I read in the newspaper that New Orleans
had been flooded and destroyed because a levee had broken.
The
information gained from this experiment could protect people from getting their
homes destroyed and being killed by floods because levees weren’t compacted in
layers enough. Lots of people would care, especially engineers trying to build
or protect people with levees.
Hypothesis
My
first hypothesis was that the more compacted layers there were, the longer it
would hold back water.
I
based my hypothesis on the fact that earthen dams and levees are usually built
layer by layer with compaction of each layer before the next one is added.
Experiment Design
The
constants in this study were:
• Width of PVC pipe
• Length of PVC pipe
• Amount of water put in PVC pipe
• Type of water put in PVC pipe
• Amount of dirt put in PVC pipe
•
Type of dirt put in PVC pipe
• Temperature where testing
• Time brick compacted dirt
The
manipulated variable was the number of layers that were compacted.
The
responding variable was the amount of time it took before the dirt plug broke.
To
measure the responding variables, I used a stopwatch and started it when I put
the water in and stopped it when plug broke.
Materials
Procedures
1.
Build system
a. Connect the 133cm in length of PVC pipe to
the 2in PVC pipe elbow
b. Connect PVC pipe valve to the elbow
c. Build plugs
i. Put 473ml of dirt in the 30.5cm length of
2in (5cm) PVC pipe
ii. Place compactor in PVC pipe on dirt then
place a 16.78kg brick
for 4 seconds on the
circle to compact the dirt.
iii. Repeat steps i. - ii. until an 8 layer plug
is created with 8 compactions.
iv. Repeat steps i. - iii. until 5 plugs are
created
v. Repeat steps i. – iv., reducing layers by
half and doubling the time the brick sits on the circle compactor
1. For the first repetition, reduce the layers
to 4 and double the compaction times to 8 seconds
2. For the second repetition, reduce the
layers to 2 and double the compaction times to 16 seconds
3. For the third repetition, reduce the layers
to 1 and double the compaction times to 32 seconds
2.
Ready Experiment
a. Place plug tube horizontally into PVC valve
so that side with the dirt is away from the valve.
b. Make sure the valve is shut
c. Support so the long pipe is vertical
3.
Conduct Experiment
a. Fill vertical pipe, 133cm with tap water to
the top
b. Start the stopwatch when you turn the valve
c. Stop the stop watch when the plug breaks
and record
4. Repeat with other dirt plugs in this
compaction group
5. Repeat with other compaction groups
6. Average results within each group
Results
The
original purpose of this experiment was to determine the effect of dirt
compaction in layers on the ability to hold water.
The
results of the experiment were inconsistent because there is no recognizable
trend. The results were low then high having no recognizable relationship.
Conclusion
My
hypothesis was that the more compacted layers there were the longer it would
hold back water.
The
results indicate that this hypothesis should be rejected, because of the
inconsistence results. The problem is that the harder you compact it the plug
is compacted so great there is no path of air for it to follow instead of the
plug breaking it is pushed out by the pressure. Though if you are compacting
the plug little air cracks will be left. If the cracks are found by the water
it will lead it out when you start to see the water come out it erodes half of
the plug in one second. The problem is that the air cracks maybe harder to
find.
After
thinking about the results of this experiment, I wonder if the type of material
used as a plug would make a difference in the time it held water. I also wonder
if the amount of time the soil was being compacted would matter at all. For example if each compaction lasted 64
seconds instead of 32, would that improve the water resistance? What if the dirt was dry, damp, or frozen? One could also test the amount of dirt used
in the plug. Would twice as much dirt
double the time water was held?
If
I were to conduct this project again I would conduct more trials probably ten
or 12. I would also test a plug with a
larger number of layers, perhaps 16.
Researched by Connor
H