Soil Consolidation

cunnins4

Hi guys, I'm trying to do a consolidation problem, but I can't figure out one part of it. It's not online and i've no access to a scanner, so i've done up the whole thing on word/excel and attached to this post. The only problem i'm having is the part highlighted in red. Where did they get 5x9.2 from?

The solution is exactly as it is in the book (from Soil Mechanics 7th Ed by Craig)

I can do every other part of it, but this is the only thing that's got me.

Any help is much appreciated!

godtabh

The 5 is the depth of the 1st layer i.e. 4+1

I'll come back to you on a bit with the other number when i figure it out

is this trintiy work?

godtabh

Best I can figure is that 9.2=19-9.8

You know where that comes from?

cunnins4

Yeah I knew the 5 was the mid depth of the first layer. I thought maybe the 9.2 was the book taking 9.2 as the value of g instead of 9.8?

Yeah it's trinity work. Where does the 19-9.8 come from?

Thanks for the help. This has been wrecking my head all day. Lost a couple of hours study to this problem alone!

godtabh

cunnins4 wrote: »

Yeah I knew the 5 was the mid depth of the first layer. I thought maybe the 9.2 was the book taking 9.2 as the value of g instead of 9.8?

Yeah it's trinity work. Where does the 19-9.8 come from?

Thanks for the help. This has been wrecking my head all day. Lost a couple of hours study to this problem alone!

the saturated unit weight of the soil is 19kn/m^3 and unit weight of water is 9.8kn/m^3.

Ah the good old Fareller or is or Orr? Good times!

cunnins4

Ahhh yes, I getcha. I was doing a tutorial on effective stress later on in the day, and when i saw your second post above it clicked with me.

Neither of the two lads actually, it's O'Kellier! (Brendan O'Kelly)

Tough enough subject though. Think I'll skip consolidation if the question's in any way difficult! I've covered the rest of the course fairly well, so I'm not gonna lose too much sleep on it!

When'd ya finish up in TCD?


Actually, since I've got your attention, sorry for abusing your help!, but would ya just tell me if this is right:

An earth embankment is constructed rapidly on a saturated silty clay layer that is underlain by sandy gravely deposits. The embankment, 5.0 m in height and 40.0 m in width is constructed using fill material with a compacted unit weight of 21.0kN/m^3. The silty clay layer has an overall thickness of 10.0m; a coefficient of volume change of 0.8 m^2/MN and a coefficient of primary consolidation of 1.5m^2/year. A drainage layer is incorporated between the base of the embankment and the top of the silty clay layer.

(i) Determine how long it will take to achieve 90% degree of primary consolidation in the silty clay layer.

So would the stress here be 21x5 giving 105kN/m^2??? And the 40m is irrelevant?

Again, sorry to keep at ye, his notes aren't the best!

godtabh

Its been 3.5 years since I've done anything like that so I'd have to look over it but not sure when I'd be able as I've an MSc project due soon (as well as work!).

The 40m is signficant I think as it gives the total weight of the soil but dont take my word on that!

cunnins4

No worries man, I've got the lecture later today, so don't put yourself out. You've been a great help.

Thanks again.

donnacha1!

Hey all,

Can anyone tell me what the upper and lower bound is in the collapse load of a soil

godtabh

Dont bump a three year old thread.

Start a new one