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Excavation by grab
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Source：Internet Author：Unknow Pubdate：2008-03-24
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Zambo (Civil/Environme)
2 Dec 07 9:08
I have seen clamshell grabs used for dredging (silt or sand) and for rock (say 3-10 tonne blasted rock) but what about excavation. Is it possible to use a wire operated clamshell to excavate a stiff clay? Or is it necessary to excavate with hydraulic equipment and use the mechanical grab just for soil movement.
dicksewerrat (Civil/Environme)
2 Dec 07 15:26
If the clay is very stiff or dry, the clamshell won't get a good bite into the material. And this will make the excavating slower. Richard A. Cornelius, P.E.
WWW.amlinereast.com
oldestguy (Geotechnical)
9 Dec 07 17:41
He is right.
However, if equipped with teeth, these buckets can do some digging in hard ground, but have little down pressure to help. 字串6
They seem to be most common handling aggregates and other loose materials in stock piles where a long reach is needed.
I've seen them regularly in use to clean out excavations in confined areas where other equipment just can't reach.
civilperson (Structural)
10 Dec 07 11:26
Good operator can drop clam from a height required to penetrate clay or other "hard" digging.
dicksewerrat (Civil/Environme)
10 Dec 07 20:40
Good cable machine operators are hard to find these days. treat him/her right. Richard A. Cornelius, P.E.
WWW.amlinereast.com
BigH (Geotechnical)
11 Dec 07 21:30
They are also used in well foundations (caissons) for bridge piers in order to dig out the material for sinking the well foundation.
字串8
PEinc (Geotechnical)
12 Dec 07 11:03
I have seen many contractors go out of their way and spend lots of money trying to use a backhoe where a clam bucket should have been used. Most contractors don't even know what a clam bucket is. Most equipment operators haven't ever done any clamming. Those operators who have done clamming seem to be retired or dead. Clamming is slow but sometimes the amount of material to be excavated is not very great and the clam may did it just as fast or faster than a backhoe.
PEinc (Geotechnical)
12 Dec 07 11:05
Sorry, I meant to type "dig it just as fast..."
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