流沙是如何工作的

Quicksand is an interesting natural phenomenon -- it is actuallysolid groundthat has been liquefied by asaturationofwater. The "quick" refers to how easily the sand shifts when in this semiliquid state.

Quicksand is not a unique type of soil; it is usually just sand or another type ofgrainy soil. Quicksand is nothing more than a soupy mixture of sand and water. It can occur anywhere under the right conditions, according toDenise Dumouchelle, geologist with theUnited States Geological Survey(USGS).

Quicksand is created when water saturates an area of loose sand and the ordinary sand isagitated. When the water trapped in the batch of sand can't escape, it createsliquefied soilthat can no longer support weight. There are two ways in which sand can become agitated enough to create quicksand:

Vibrationtends to enhance the quickness, so what is reasonably solid initially may become soft and then quick, according toDr. Larry Barron(t)he New South Wales Geological Survey.

The vibration plus the water barrier reduces the friction between the sand particles and causes the sand to behave like a liquid. To understand quicksand, you have to understand the process ofliquefaction. When soil liquefies, as with quicksand, it loses strength and behaves like a viscous liquid rather than a solid, according to theUtah Geological Survey. Liquefaction can cause buildings to sink significantly during earthquakes.

While quicksand can occur in almost any location where water is present, there are certain locations where it's more prevalent. Places where quicksand is most likely to occur include:

The next time you're at thebeach, notice the difference in the sand as you stand on different parts of the beach that have varying levels of moisture. If you stand on thedriestpart of the beach, the sand holds you up just fine. The friction between the sand particles creates a stable surface to stand on.

If you move closer to the water, you'll notice that the sand that ismoderately wetis even more tightly packed than the dry sand. A moderate amount of water creates the capillary attraction that allows sand particles to clump together. This is what allows you to build sand castles.

But beach sand could easily become quicksand if enough water were thrust up through it. If anexcessive amount of waterflows through the sand, it forces the sand particles apart. This separation of particles causes the ground to loosen, and any mass on the sand will begin to sink through it. In the next section, you will find out how to save yourself if you happen to fall into a pit of quicksand.

The more you struggle in quicksand the faster you will sink. If you just relax, your body will float in it because your body is less dense than the quicksand.

If you ever find yourself in a pit of quicksand, don't worry -- it's not going to swallow you whole, and it's not as hard to escape from as you might think.

The human body has adensityof 62.4 pounds per cubic foot (1 g/cm³) and is able to float onwater. Quicksand is denser than water -- it has a density of about 125 pounds per cubic foot (2 g/cm³) -- which means you can float more easily on quicksand than on water. The key is to not panic. Most people who drown in quicksand, or any liquid for that matter, are usually those who panic and begin flailing their arms and legs.

It may be possible to drown in quicksand if you were to fall in over your head and couldn't get your head back above the surface, although it's rare for quicksand to be that deep. Most likely, if you fall in, you will float to the surface. However, thesand-to-water ratioof quicksand can vary, causing some quicksand to be less buoyant.

“同样的道理,如果流沙深,in up to your waist, it would be very difficult to extract yourself from a dense slurry, not unlike very wet concrete," said里克Wooten, senior geologist for Engineering Geology and Geohazards for theNorth Carolina Geological Survey. "The weight of the quicksand would certainly make it difficult to move if you were in above your knees."

The worst thing to do is to thrash around in the sand and move your arms and legs through the mixture. You will only succeed in forcing yourself farther down into the liquid sandpit. The best thing to do is to makeslow movementsand bring yourself to the surface, then just lie back. You'll float to a safe level.

"When someone steps in the quicksand, their weight causes them to sink, just as they would if they stepped in a pond," Dumouchelle said. "If they struggle, they'll tend to sink. But, if they relax and try to lay on their back, they can usually float and paddle to safety."

When you try pulling your leg out of quicksand, you are working against avacuumleft behind by the movement, according to "The Worst-Case Scenario Survival Handbook." The authors of the book advise you to move as slowly as possible in order toreduce viscosity. Also, try spreading your arms and legs far apart and leaning over to increase yoursurface area, which should allow you to float.

While quicksand remains the hackneyed convention of bad adventure movies, there's very little to be afraid of in real life. As long as you keep a cool head in the situation, the worst result will be a shoe full of wet sand.