culvert design

[matthewliew]

Dear Dr.Quek,

My name is matthew liew and i join the 8th workshop on end of june 2009. It has been 2 years and i am having trouble remembering how tp design culvert for the workshop no.3. I would appreciate if u could assist me in the following:-

1. For the design of culvert, what does N (No. of cells) in table 4.1 represents? Does it represent the no. of pipe culverts or box culverts?

2. According to your sample table 4.1, the pipe culvert c2, does not have value for B but only D. Does the D represent Diameter of pipes?

I would appreciate if u could revert to me as soon as possible. It is good to hear from u after awhile.

Thank you

Matthew liew

[drquek]

Hi Mathew,

Here are answers to your questions:

1. N represents the no. of pipe culverts or box culverts.

2. D represents the Diameter of pipes.

[matthewliew]

Dear Dr.Quek

Thank you for your reply. But I am still having problem trying to design the culvert.

1. What is the difference between subcritical and supercritical? Does it matter which of thetwo is true?

2. Where to obtain stage and q to plot chart of nomograph?

3.What is the purpose of table for culvert design? What kind of info is used to compare?

Thank u for time taken and ur patience. Hope to hear from u soon.

Matthew

[drquek]

The table is just an approximation.

You should check it with the nomograph.

The input required for the spreadsheet are highlighted in yellow.

It is quite intuitive for you to use. Try it.

[matthewliew]

Dear Dr.Quek

Thanks for your patience. Kindly comment the following:-

1. What is the significant of subcritical and supercritical in the culvert design in your spreadsheet ; drquekDetention1a.xls? This is because u have used stage (1.73 and 5.25) from Trial No.6 for the development of the graph for stage-discharge relationship. The above showed supercritical for both Q50 and Q100.

2. what if u have -value for CRI A(100yr WL)? Kindly refer to Trial no.2 of culvert design in your spreadsheet ; drquekDetention1a.xls.

Thank you

[drquek]

1. The subcritical and supercritical in the culvert design in my spreadsheet help us to see if our design section is flowing under sub/super critical condition. Most culverts are designed for subcritical flow.

In the detention spreadsheet, however, this has no significance as we only want to develop the rating curve for our computation.

2. As I mentioned in the workshop, don't worry about CRITERIA A, B or C. These are just for railway embankment design. You can modify them to suit your purpose e.g., if you designing highway embankment.

[matthewliew]

Dear Dr.Quek


Thank you for your comment.

1. Would it fair to say that it would be good enough to use the nomograph only to generate the discharge for culvert. That means i could ignore the spreadsheet results?

2.I am having problem trying to generat discharge for the emergency spillway.
kindly advice.

3. would it be possible to meetup for clarification on the culvert design for hydrograph?

thank you

[drquek]

Hello Matthew,

1. The spreadsheet is only a quick approximation to the "correct" answer obtainable from the nomograph. As I said in the Workshop, the spreadsheet saves you a lot of time when dealing with repetitive task of designing a lot of culverts e.g., highway and railways.

2. I am not sure what your problem is. May be you can email me the problem.

3. Are you a participant of the workshop? I can help you if you attended one of our earlier workshop.