漂流-低落差堰坝-技术，安全讨论

原子弹 · 2006-08-08 05:56

悲痛！！

为了漂流活动安全，很想对事故的详细情况的技术细节进行调查

1)  橡皮艇被河水冲翻全部落水时
河水流速？
落差？
漩涡？

2）橡皮艇是否破损？
3）橡皮艇的稳性计算？
4）橡皮艇的适航区说明（或证书）

原子弹 · 2006-08-09 00:11

据了解，此次驴友赴连平的活动发起人为惠州的“独啸山林”，他们自发组织到连平县上坪镇采摘品尝水蜜桃。途经连平县内莞镇时，驴友觉得此处河水清澈，于是停车组织漂流。当时，6人分乘五辆皮艇下水，独啸山林带着一位女驴友乘坐于一条艇上。然而台风“派利安”带来降雨，河流水涨。五条皮艇漂出二三十米远处，正逢一个大坝，坝上水面与坝下水面的落差在两米到三米之间。由于水流很急、水量很大，坝顶水落下打到坝底水面上时，形成低凹，造成坝下水不是往前流，而是倒流回坝底，形成大大的漩涡。由此，5条艇从坝底顺水而下时正好落入漩涡之中，全部翻转，6人全部落水。6人在水中努力自救、互救，岸上另3名驴友赶紧准备好绳索抛入水中，艰难地将3人救起。独啸山林在被水流卷走前，曾几度用力地将身边的女孩推向岸边，将生还的机会让给女孩。令人感动的是，在生命的危急时刻，5位男性驴友都经受住了人性的考验，遵循遇险先救女人的原则，先极力帮助女孩脱险。女孩幸运得救，“海湾”、“孤叶”溺亡，“独啸山林”失踪。

    事后，有来自几个城市的约50名驴友赶往事发地点帮助处理善后和搜救“独啸山林”事宜，配合当地警方工作。死者家属亦赶往事发地。据有经验的驴友推断，两名溺亡及失踪的驴友估计所穿救生衣系得不够紧，在现场找到3件救生衣，而另3名生还者遇险到生还的一刻仍然穿着救生衣。

原子弹 · 2006-08-10 05:30

引用游民描述：

     “ 在8.5事件中，是和队伍一起去的畅游金牌司机___小宝，在公路边（事故水坝的上方，当时正和广州一名女队员在一起）首先发现六人翻落水中，并处在旋涡中无法脱离。敏锐地察觉到发生意外了，回身在车内找出一条约3米的辅绳，飞跑下到水坝的右边的水泥墙上，接近落水者的地方，抛下绳子开始营救。但由于水的力量十分巨大，他一个人的力量根本没法把其中任一个人拉出旋涡。好在有两个还没冲下水坝的队友发现情况马上赶过来一起合力拉，水中人员也需多次才能握住绳索，费了不少时间和气力才把二男一女拉出旋涡，这时回头已不见其余三人了，也没人注意到他们是怎么消失的。

水坝下波涛翻滚的旋涡令落水者无法脱离。

坝下水深探过不到两米，但水下有多块大石头，从坝上冲下的大水撞击大石后形成翻滚回旋涡，产生巨大力量令人无法挣脱，等人体力耗尽马上就被它吞噬。据当地人说平时这里水量只有一半左右，那天因为有一座水电站关闭了，令流经大坝的水量大增一倍，这也是导致意外的一个原因。“

这一事故太重要了，为了以后漂流人员的安全，需要基于多方的描述，专业的判断。
事故的过程描述有不同，但事故发生的条件很清楚

1）落差2 -3 米
2）流量大 （游民是否测过流速？投一木块，看速度）
3）河道收窄区
4）有旋涡

原子弹 · 2006-08-15 08:33

Low-head dams: A not-so clear and present danger
低落差堰坝：看似無害，實際上暗藏危险

by Virgil Chambers, Executive Director, National Safe Boating Council
Rivers can be treacherous, not only because of the tremendous power they possess, through the movement of flowing water, but because of structures they flow over, around and through.
河流暗藏危险，不仅是因为它流动时具有的巨大能量，还因为它流过的结构，河床情况。
Hazards like "strainers," fallen trees and debris collecting between rocks and bridge piers that can trap floating objects, are generally conspicuous. And those familiar with the dynamics of moving water know how the force of the water, as it comes in contact with different obstructions, can actually hold objects.
桥墩，大石间聚集的树干，漂服物形成“筛”。河流快速流过“筛”，进入这一区的人，物可能被网住，危险是显然的。
Bridge piers and rocks are potentially dangerous basically because they don't move and the water does. If the water is moving fast enough, anything or anyone coming in contact with these structures can be held tight against their upstream side. Once pinned in this way, escape is difficult. We can easily understand the danger and what is happening when water holds an object against an obstacle.
桥墩，大石暗藏危险。河流快速流过桥墩，大石结构时，桥墩，大石迎流面减速增压，进入这一区的人，物可能被紧紧吸住，难逃脱。
However, the distinction is not so clear with the dangers associated with the river's most perilous obstruction, the low-head dam. It is a man-made structure, typically built to back up water in a reservoir for a variety of reasons. This wall-like structure pools the water as it flows over the crest and drops to the lower level.
河流最可怕的障碍物，低落差堰坝危险，却不很清楚。低落差堰坝是人造结构，形成水库。河流流过坝顶，落入坝底。
This drop creates a hydraulic, which is a backwash that traps and recirculates anything that floats. Boats and people have been caught in this backwash. A person caught in the backwash of a low-head dam will be carried to the face of the dam, where the water pouring over it will wash him down under to a point downstream called the boil. The boil is that position where the water from below surfaces and moves either downstream or back toward the dam. A person who is caught in a low head dam struggles to the surface, where the backwash once again carries him to the face of the dam, thus continuing the cycle.
河水坠落产生水动力回流，回流扑捉浮体，就地打转。被低落差堰坝回流扑捉的人和艇，被带回坝面，河水坠落泼向人和艇向下进入涡底。水下涡底的水分叉，部分流向下游，部分流回坝面。被低落差堰坝回流扑捉的人努力浮出水面，又被带回坝面，循环。

to be continue.

原子弹 · 2006-08-16 00:55

To complicate matters, these dams are usually loaded with debris, such as tires and logs on the surface and rocks

and steel bars just below, posing additional problems should a person get trapped in this dangerous structure.
这些堤坝通常会聚积水面上漂浮物如有轮胎，枯木，水底有石头和突出的钢筋，事情会更复杂。陷入这一危险结构的人会经历更多麻烦。

Dams do not need to have a deep drop to create a dangerous backwash. During periods of high water and heavy rains,

the backwash current problems get worse, and the reach of the backwash current is extended downstream.
无需多深堤坝就能形成危险的回流。在高水位季及多雨季节里，回流的水流问题就更严重，回流的区域可能会扩展到下游。

Small low-head dams that may have provided a refreshing wading spot at low water can become a brutal death trap when

river levels are up. Simply put, it is not the drop of the dam which is the lethal danger, but the backwash current.

This backwash current is governed by volume of water and flow.
低落差堰坝在低水位时，河流流过坝顶，直接落入坝底冲击河底形成“锅底“。

当水位上升时“锅底“可能会产生致命死亡的陷井。从坝上落下不是致命的，但回流是致命的。回流的水流是由水量及流速决定的。

From downstream, you may not realize the danger until it’s too late. From upstream, low-head dams are difficult to

detect. In most instances, a low-head dam does not look dangerous, yet can create a life-threatening situation. You

should always pay attention to warning signs, markers or buoys and keep well clear of low-head dams.
从下游看，你可能没有意识到危险，当你意识到时，已经太迟了。从上游走，低水头坝不易发觉。在更多的事例时，低水头坝看起来不怎么危险，但是可能会产生危及生命的情况。您必须小心注意警告牌，标记及浮标，尽早避开低落差堰坝。

（堰坝前200米- 1000米上岸，河流流过低落差堰坝，流断面变小，流速加快，艇可能停不来）

原子弹 · 2006-08-16 05:45

逃生路

原子弹 · 2006-08-16 06:12

http://video.google.com/videoplay?docid=-6846124409391034920

试验录像

原子弹 · 2006-08-22 05:54

慢慢聚集到理性讨论与技术交流上面来了。
有时间会多译相关国外技术资料。