Mansour Sample Problem 8.8

[divs]

Hello,

I have a question regarding the Sample Problem 8.8 (on page 185 of Mansour's books). How were the volumes -29 (fill b/w stations 11+21 and 11+40) and 568 (cut b/w stations 11+64 and 12+00) calculated? Please see attached figure and table.

Thanks,

Divya

 

[bradlelf]

I cannot see the "attached" figure or table. Please retry or type it out.

 

[divs]

Oops..the table and figure are attached.

 

[ptatohed]

Divya,

I have spent an hour on this (I am at home on paternity leave, not at work ) and I can see exactly why you are asking about these two table values (The 29CY of fill b/t Sta's 11+21 and 11+40; and the 568CY of cut b/t Sta's 11+64 and 12+00). When I use the Average End Area (AEA) Method to calculate the C/F volumes, my answers match all of the table answers except the two you are questioning. Using the AEA Method, I get 34.8CY Fill (instead of 29.0) and 553.3CY Cut (instead of 568.0). Is that what you get?

It appears that the AEA Method is being used to calc all the volumes, even at locations where one of the areas is zero and the Pyramid Formula could be used. Also, I don't think we have enough information to use the Prismoidal Formula. So I think the AEA Method is the only method to use.

Is there more to the problem not shown in your pictures? What is shown on the right side of the Fig 8.6 table?

Sorry, I couldn't help much. If you figure it out please share.

 

[bradlelf]

Here is what I get with AEA:

End Area

Volume

cut

fill

cut

fill

1000

0 sf

992 sf











0 CY

2,617 CY

1100

0 sf

421 sf











0 CY

189 CY

1121

0 sf

65 sf











12 CY

34 CY

1140

34 sf

31 sf











79 CY

14 CY

1164

144 sf

0 sf











553 CY

0 CY

1200

686 sf

0 sf











2,970 CY

0 CY

1300

918 sf

0 sf





I find it a bit odd that there is a shrink factor and not a swell factor though. Typically you would have a swell with the cut material.

Seems to be a mistake in the book ... have you checked for errata?

 

[bradlelf]

Let me try this again:

1000 00 992

00 2617

1100 00 421

00 189

1121 00 65

12 34

1140 34 31

79 14

1164 144 00

533 00

1200 686 00

2970 00

1300 918 00

 

[ptatohed]

Brad, in Post #6, did you mean 553 (not 533), like you had in Post #5? I'm asking because I get 553.

 

[bradlelf]

Yes typo 553

 

[divs]

ptatohed & bradlelf, these are the values I was getting too. I just wanted to make sure I wasnt doing something wrong Thank you both for your replies! I tried to search online for the errata, but couldnt find it.

 

[ptatohed]

ptatohed & bradlelf, these are the values I was getting too. I just wanted to make sure I wasnt doing something wrong Thank you both for your replies! I tried to search online for the errata, but couldnt find it.

Did you contact Dr. M./PassPE.com?

http://www.passpe.com/contact.html

 

[divs]

I just sent him an email, lets see if I can find the errata. Thanks again!