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Name: Steve
Status: educator
Grade: 9-12
Location: IL 
Country: N/A
Date: 5/20/2005


Question:
How can mud slides be prevented?


Replies:
One thought at a time. Mud slides are a term usually applying to clay, but it can be any soil. There is a "natural angle of repose" for a soil. This means that over time the soil will go to a certain slope ( its natural angle).

Water is involved, when the material is dry the slope can be more closer to vertical. If you think of the grains of soil, when they get surrounded by water it reduces the tendency to stick together. For clay it is called cohesion. Somewhere along the line toward saturation, where the grain is totally surrounded, the balance between the ability to stay together, sticky or cohesion versus the weight of the overlying soil yields. The soil slides along a angle. The angle of repose.

Now, preventing sliding, means fighting nature. You would have to keep water from soaking into the soil.

Not an easy task, usually the event causing the concern is humans not understanding soil properties. Consider the houses built close to slopes. The angle of repose, I mentioned would be from the bottom to the top. You will see, houses built on posts. The posts go deeper beyond the slope into the soil beneath the angle, looking for anchorage. If done correctly the soil could slide away, out from under the house. The other option is enough pipes and material that can drain the water away from soaking into the soil. "You can't fight Mother Nature", was in a commercial, it can be done, but not easy and it costs.

James Przewznik



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