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路面塌陷的原因

How Do Sinkholes Form?

有一些很复杂的土木工程问题
Some of the most complex civil engineering problems
源于水和环境相互作用
stem from the interaction of water and the ground.
这听起来很普通
It sounds mundane
你可能已经在新闻上看过它引起的事件
but there’s a good chance you’ve seen one of these on the news.
地面怎么会突然开裂
How is it possible for the ground to simply open up
吞没掉它周围的一切呢?
and indiscriminately swallow anything or anyone that happens to be around?
我是Grady 这里是《实用工程学》
I’m Grady and this is Practical Engineering.
在今天的节目里 我们讨论天坑
On today’s episode, we’re talking aboutsinkholes.
本视频由Blue Apron赞助
This video is sponsored in part by Blue Apron.
稍后详细介绍
More on that later.
我们都知道侵蚀现象
We all know about erosion.
它让地下的土石暴露出来
This is the process that takes soil and rock from the earth’s crust
流失到其他地方
and moves it somewhere else.
有很多情况会造成侵蚀 比如
And there’s a lot of ways this can happen
风化 滑坡 磨蚀和冲刷
wind, landslides, abrasion, and scour.
但值得一提的是
But here’s the thing,
没有哪个因素的效果比得上流水
none of it compares to just the movement of water.
水的侵蚀能力非常强
Water is the great eroder.
不知道你是否好奇过
If you ever find yourself wondering
特征地貌是怎么形成的
how did this particular feature of the earth come
或者为什么会形成这样的地形
to be here, or why is the ground shaped like so
又或为什么它们看起来是这样的
or just why are things the way that they are
多数情况下 造成这些结果的原因是流水
more often than not the answer is pretty much just water.
水流搬运沙石的能力取决于几种因素
The ability of water to move soil or rock depends on several factors.
水流越快越湍急 侵蚀性越强
The faster and more turbulent the flow, the more erosive it is.
像沙砾之类的大颗粒
Larger particles like gravel and more
就比淤泥或是粘土之类的小颗粒更耐侵蚀
resistant to erosion than small particles like silt or clay.
最后 除了物理侵蚀
Finally, rather than physical erosion,
某些物质还可溶于水
some materials are soluble in water
就像糖或盐一样
just like sugar or salt,
它们浸入地下水中时间长了就会被腐蚀
and can be eroded just by dissolving into the groundwater over time.
大部分人认为侵蚀发生在地表
Most of us think about erosion on the surface of the earth
但侵蚀同样也可以在地下发生
but erosion can occur in the subsurface as well.
科学家和工程师为这个过程取了一个新颖的名字
In fact, scientist and engineers have a verycreative name for just such a process:
暗蚀
internal erosion.
如果地下具备了所有侵蚀条件
If just the right factors come together in the subsurface,
就会发生一些有趣的事 比如天坑
Some interesting things can happen, including sinkholes.
首先我们看一个非侵蚀性地下水流动模型
But let’s look at a non-erosive exampleof groundwater movement first.
我拍这个视频的时候
This is from a video I made
这节目还不叫《实用工程》
before the channel was even called Practical Engineering.
在视频中水从左侧障碍向下流动
Water is flowing from the left side of the demo
然后上升至右侧
under an obstruction and over to the right.
我们可以看到:第一 水流动得很慢
Notice two important things: first, the movementof water is slow.
沙子中没有足够的空间
There’s not a lot of open space between all that sand
所以水流过去需要很长时间
so it takes time for water to flow through.
第二 沙子被封在了玻璃板里
Second, the sand is confined.
即使它想移动 它也没地方可去
Even if it wanted to move there would be nowhere for it to go.
如果不满足这两个条件 那么就会产生天坑
If those two conditions go away, that’swhen sinkholes happen.
大部分天然天坑出现场所
Most natural sinkholes occur in areas
都有大量碳酸盐岩的沉积物 比如石灰岩
with large deposits of carbonate rocks, like limestone.
很长一段时间后
Over long periods of time,
流动的地下水就会溶解岩石
groundwater flowing through the subsurface can dissolve the rock,
产生孔洞和连通的隧道
creating voids and open tunnels.
事实上 这就是大部分洞穴形成的过程
In fact, this is how most caves are formed.
这些隧道和孔洞大幅改变了地下水流动
These tunnels and voids create a significant change in the character of groundwater flow.
首先 它们会让水快速流动
First, they allow water to flow quickly just
就像在管道里一样 让它更具有侵蚀性
like it would through a pipe, making it more erosion.
第二 它们为冲走土壤提供了空间
Secondly, they create a space for soil to washaway.
在这两种情况下
With those two conditions,
任何可溶解的土壤都有被溶解流失的风险
any soil overlying a dissolution feature runs the risk of eroding away from the inside,
最终形成一个天坑
eventually leading toa sinkhole.
但不是每一个天坑都是自然形成的
But not every sinkhole is formed through naturalprocesses.
事实上 最近许多著名天坑都是人造成的
In fact, many of the most famous sinkholes in recent times have been human-created.
就像一个被溶解到基岩的洞穴
Just like a cave dissolved into the bedrock
可以像管道一样 让地下水运走土壤
can act like a pipe and allow groundwater to carry away soil
真正的管道同样可以做到这些
an actual pipe can do the same thing.
并且它们不受特殊地形的影响
And actual pipes aren’t limited to areas witha specific geology.
当你观察任何一个城市的地下空间
If you could take a look into the subsurface of any open area
你就能看见绵延交错的阴沟和排水管道
you can see miles and miles of water, sewer, and storm water drainage pipes.
很不幸我们不能透视地底
Unfortunately we can’t see into the ground,
所以我建了这个装置来示范它的运作过程
so I built this demonstration so we can see for ourselves how this works.
只需要一点沉降和移动
All it takes is a little bit of settlement or shifting
它就能打开其中的缺口
to create an opening in one of these pipes
开始暗蚀
and allow internal erosion to start.
为了模仿它的效果 我在管道中开了个缺口
I added a gap in my pipe to simulate thiseffect.
管道中的流水
Water moving through the pipe is able to
就可以冲刷掉附近的土壤
dislodge the adjacent soil and carry it away.
注意这时地面并没有什么异常
Notice that there’s no signal on the surface that anything is awry.
当大量的土壤被冲走 就形成了地下空间
As more soil is washed away, the subsurfacevoid grows.
根据我们先前说过的土壤的成分不同
Depending on all those soil properties we talked about earlier
这个过程会默默地进行几天甚至几年时间
this process can take days to years before any one notices.
我们的许多地下设备被直接放在道路下
Many of our subsurface utilities are placed directly below roadways
像是在天坑上最后搭好的那座桥
and the paving often acts as a final bridge above the sinkhole
天坑就隐藏在下面的空间
hiding the void below.
路面塌陷只是时间问题
It’s only a matter of time before anything above is swallowed up.
但天坑不是暗蚀的唯一危害
Sinkholes aren’t the only problem causedby internal erosion.
还有一种特殊的暗蚀叫管道侵蚀
A specific type of internal erosion called piping
它是土制防洪堤和水坝崩溃的首因
is the most common cause of failure for earthen levees and dams,
比如爱达荷州的泰顿坝在1796年
including Teton Dam in Idaho which killed 11 people
导致十一人死亡和数十亿美元损失的溃坝
and caused billions of dollars of damage when it failedin 1976.
或许我会在后续视频中再做一个管道模型
Maybe I’ll build a piping demonstrationsomeday for a separate video.
暗蚀是自然过程
Internal erosion can be a natural process,
但天坑的形成 有时是因为糟糕的决策
but sometimes sinkholes can form due to bad decisions, bad construction,
糟糕的设计 或者只是偶然的建筑事故等等
or just bad luck with human-made infrastructure as well.
土木工程师在设计可能与水接触的建筑时
It’s just one of the many complex failure modes
在诸多复杂破坏模式中必须考虑的
that civil engineers must consider when designing a structure
一个因素就是最大侵蚀量
that might interact with water, the great eroder.
感谢收看 欢迎讨论
Thank you for watching, and let me know whatyou think!
感谢Blue Apron大力支持
Big thanks to Blue Apron for sponsoring thisvideo.
我们正在搬家
We’re in the process of moving
在新房子里忙着拆包裹
and just starting to get unpacked in the new house.
准备干完后去买些食材
The last thing on my mind is going out to buy groceries.
Blue Apron将你的食物送货上门
Blue Apron delivers all the fresh ingredients you need,
让你可以在家里以最完美的搭配
right to your doorstep, in exactly the right proportions
做最美味的食物
to create deliciousrecipes at home.
在不需要准备食材的情况下 做饭就是一种享受
It’s essentially just the fun parts of cooking with none of the chore
这正是我们这周需要的
which is exactly what we needed this week.
如果你对它感兴趣
If that sounds like something you’d be interested,
你可以免费找到它
you can find out for free.
前一百个点击指定网址的人
The first hundred people that click on the link in the description
都会无偿拿到三份blue apron的餐饭
will get 3 blue apron meals with no commitment whatsoever.
如果你喜欢 你可以参加订阅
If you like it, you can sign up for a subscription,
如果你不这么做 嘿 你就只能得到三份饭
and if you don’t, hey, you just got three free meals shipped right to your doorstep.
再次感谢收看 欢迎讨论
Again, thank you for watching, and let me know what you think!

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视频概述

浅析地面塌陷的原因,了解天坑的原理和形成过程

听录译者

收集自网络

翻译译者

未完待续

审核员

审核员_ZB

视频来源

https://www.youtube.com/watch?v=e-DVIQPqS8E

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