Creating a crater on the ground

[Ugarik]

This is pretty straight forward. Why do we use pulverization of rock value for such feats? Where is no way some soil can be as hard as pure rock.

I think found the table we can take destruction values from:

Fragmentation: (shear strength of meduim clay)

0.05 - 0.1 J/cm^3

Pulverization: (compressive strength of hard soil)

0.4 - 1 J/cm^3

 

[Mr. Bambu]

Moved this to Calc Group discussion since it is more relevant there.

Think it could work? Not sure of the legitimacy.

Also frag should vary from 0.05 to 0.4 J/cc based on the document.

 

[Antoniofer]

The best way to confirm this is to look into other sources; if they possesses values of the same range then we can asure is legit.

 

[Mr. Bambu]

Right.

Also, for most craters they are in stone- urban settings or rocky terrains or such like. This would be used... rarely. Still nice to get a value though.

 

[Antoniofer]

It depends of what type of environment is refering these values.

 

[Ugarik]

I found another document with really simiral values for compressive strength

just so you know kN/m^2 is the same thing as kPa

 

[Antoniofer]

Actually, Pa = N/m^2, so MPa = MN/m^2

 

[Ugarik]

I now I just misspelled it. Anyway those values should be correct because they close enough to each other

 

[Ugarik]

I found 2 more stuides (one of them in Russian) with exacly the same results. Apparently those values are the most common.

 

[Mr. Bambu]

Seems consistent enough to me then. This and the values for wood should be added to the Calculations page.

 

[Ugarik]

Most sourses say that the shear strength of soil is about 150 kPa (0.15 J/cm^3). That's stiff clay value from the first document. Also the Russian source I took a table above says that the shear strength of soil is about 1/3 of its compressive strength which is also close enouth.

So:

Fragmentation: 0.15 J/cm^3

V. Fragmentation: 0.15-0.2 J/cm^3

Pulverization: 0.4 - 1 J/cm^3

 

[Mr. Bambu]

Should probably just leave V. Frag as 0.2 J/cm^3 since it should be higher than Frag, other than that, looks good.

 

[DarkDragonMedeus]

I kind of thought of dirt as rock that's already pulverized for feats like these, but this does make sense to me as well. Dirt clots do fragmentize very easily yes.

 

[DMUA]

Another thing to consider is that for massive bits of land, there's still plenty of rock. It's not 100% rock of course, in fact, it's as small as 45%. Still, worth considering. That, and water content for Vaporization feats.

 

[Ugarik]

Where did you get 45% from? But I can agree that we shouldn't use those values for massive crators

 

[DMUA]

this

 

[Ugarik]

this

This is not how it works. Even if soil is 45% rock particles its total compresive strength is still 0.4 - 1 MPa. It can't be split into "rock" and "not rock".

 

[Antoniofer]

I think that these porcentages are already involved in the experiments.

 

[DMUA]

Ah. I see.

Still, it would come into play as per Vaporization calcs

.... I'll be ugh

Going to downgrade SAO Tabletop now

 

[DMUA]

Just to be clear, using water and rock content would be okay in cases of vaporization, right?

 

[Ugarik]

I think so

 

[DMUA]

thank you.

 

[DMUA]

Actually, now that I think about it, we should probably assemble calcs to fix.

Just off the top of my head, this

 

[Mr. Bambu]

Ehhh on that scale, no. Dirt generally doesn't go that deep into the ground.