Meaning of 50th Percentile ( median) Armour Stone Revetment Stone Size

[Michael Matkowsky]

If a coastal engineer specified 4 to 5 ton armour stone and the construction had a range of sizes, say 3-5 ton and over
50 % of the stone was 4.5 ton or more, is the engineer's spec being satisfied ?

 

[SlideRuleEra]

The way I have seen "median 50th percentile weight" (W₅₀) used is a single number, say 4.5 tons. Then 50% of all the stones weight less than 4.5 tons and 50% of all the stones weigh more than 4.5 tons. All of the stones (100%) are within the specified 4 to 5 ton range.

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[Michael Matkowsky]

Is there a limiting weight for the under size stone? Where do these rules come from ?

 

[SlideRuleEra]

1) Is there a limiting weight for the under size stone?

2) Where do these rules come from ?

1) All of the stones (100%) are within the specified 4 to 5 ton range.

2) US Army Corps of Engineers "Shore Protection Manual, Volume II"

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[Michael Matkowsky]

Thank you