Science Buddies: "Ask an Expert"

Hi,

We are trying to do a science experiment to see the effects of liquefaction.
We are thinking of the following experiment, but have lot of doubts.

1. We want to use 3 PVC pipes abt 2 ft in height . Drill holes in it.

2. We want to make sandy loam ( any ideas on how to prepare such a soil?)

3. Fill it and saturate it ( again how do we do it ?4. insert dowels in holes

4 a. Add weights on top ( where we do get weights and what are weights?)

5. simulate earthquake ( how do we do it ?)

6. try to pull out dowels to see if soil compaction occurs.

Is soil compaction good or bad ? what will happen to soil which has undergone liquefaction ? Will it get compacted more or less ? Will more force be required to remove dowels or less ? what does it tell us .

This is the control

We want to filll some bark with sandyloam and fill the third pipe with stryfoam and see what happens ? what would happen ? Will it reduce liquefaction and why ?

It really helps to understand more about these and any help is greatly appreciated .

Thanks

Hi,

This sounds like a very interesting and worthwhile project. The science buddies website has an abbreviated project idea for this, but it does not contain the details that you need. Maybe you could help us improve this project idea after you complete your project.

https://www.sciencebuddies.org/science- ... p037.shtml

This website shows a video with an experimental set up that would work for your project without the need to drill holes in the PVC pipes and it shows how to simulate an earthquake.

http://www.youtube.com/watch?v=YlSuosOTAV0

This website describes factors that lead to soil liquefaction and it includes links to various research projects that might give you an idea to design your experiment.

http://www.ce.washington.edu/~liquefact ... /main.html

This website includes a good description of different soil types. For your project, you would want to classify your soil according to particle size and amount of organic matter.

Good luck!

Donna Hardy

Hi,

I have looked into the links provided. The first one give 'page not found' and the others still leave all the questions I have asked unanswered. Atleast, It would help if I get more specific answers to the questions to even proceed further .
Hope somebody can help me.

Thanks in advance,

Hi joeyk,

That sounds like a great project. In general, if you haven't been to this website yet, I think you will find it good for background knowledge. http://www.ce.washington.edu/~liquefact ... /main.html I'll answer your questions and I have a couple of my own, too.

http://en.wikipedia.org/wiki/Loam I found this article short, but now I know snady loam is 40% sand, 40% silt and 20% clay. I would start at your local garden supply store and see if you can get it there (or the components to mix it). Make sure it is well mixed and you make one batch for the whole experiment so as to control variability.

I think I would wet the soil before filling the pipes so you have better control over how wet it is (hard to judge with the soil in the pipe - which is the same reason I consistantly over-water my plants. Mix it up well with your hands or a shovel.

Some questions for you -
How wide are the pvc pipes? What are the dowels and weights for, and what do you expect them to do?

To make an earthquake, I have two ideas to make them shake. You want to be consistant in shaking the different tubes, so you can either mount them together and shake (depening on their size, you may want to place it on a large board placed on a wagon. you can use the handle (and a few helpers) to create an earthquake. The other option is to shake them one at a time, but use a time to shake exactly as long. Try to shake them the same number of times and hardness. If shaking does not produce a good earthquake, you could try dropping from a few inches (wear saftey goggles in case sandy loam flies about.

In number six, you'll pull out the dowels. You will need a way to measure if the dowels are easier or harder to pull out. I amnot sure how to do that.

Your questions answered:
Is soil compaction good or bad ? if you house is built on a place where soil compaction is, that would be bad.
what will happen to soil which has undergone liquefaction ? It gets very weak. It has too much water trapped and so the soil particles have lost contact with each other, making it behave like a liquid.
Will it get compacted more or less ? It doesn't compact well because of the water in there
Will more force be required to remove dowels or less ? This it would be easier to pull the dowels out. We need a way to measure that though.
what does it tell us . Easier to pull out because the soil is behaving like a liquid.

I hope that helps!
Tonya

Hi,

Many thanks for the information.

>>Some questions for you -
>>How wide are the pvc pipes? What are the dowels and weights for, and what do you expect them to do?

PVC pipes are 10 inches wide. I am thinking dowels are for checking soil compaction and weights are to measure how much they sink . Not really sure , but this is what I think.

For the loam , I got garden soil and sand . I could not find other material . Can I mix them and make the loam?

Also, I want to add bark to another and styrfoam to another ( any ideas on how much to mix - proportion . i,e sandloam + how much bark and sandyloam + how much styrfoam.

What to expect or hypothesize? Will liquefaction be reduced ? If reduced what could be the explanation ?

Any more answers is always helpful.

Thanks Again

You are going to measure with the weights. I think thats a good idea, and it shows you have thought your project through very well.

If you don't have any clay to add, the experiment may still work. It's a good idea to try adding other media too.

What to expect or hypothesize? I expect liquified soil will make the dowels easier to remove.
Will liquefaction be reduced ? Adding other media may reduce liquifaction.
If reduced what could be the explanation ? If liquifaction is reduced, possibly it is due to the other media added. Possibly it absorbs moisture, or ortherwise contributes to the water being able to escape during the earthquake, resulting in compaction instead of liquifaction.

Have fun with your project! It sounds like you are learning alot about soils and movement in an earthquake.