Drainage manhole design
Drainage manhole design
(OP)
Hi there:
In a project, I am ask to design a drainage manhole structure. I haven 't done it before. Is there anyone got any tips on it? I will also need to provide the structural aspect of the design, such as the re-bar, concrete etc. If there is a example will be great.
tsli
In a project, I am ask to design a drainage manhole structure. I haven 't done it before. Is there anyone got any tips on it? I will also need to provide the structural aspect of the design, such as the re-bar, concrete etc. If there is a example will be great.
tsli





RE: Drainage manhole design
RE: Drainage manhole design
http://www.concrete-pipe.org/pdfs1/DD_20-06.pdf
RE: Drainage manhole design
Thank you for your input. Actually I had practice in U.S. before, I even got a PE in Mass. Anyway, I'm in Hong Kong right now due to lack of job back home. I need to design a 10mX11m special manhole. Well, I think is more like a shaft or tank. So, any idea I can got some tipes. By the way, got anything in metric?
tsli
RE: Drainage manhole design
What is the expected flow through the manhole?
Is this a sewer or a rainwater MH?
Is this a junction MH
How (or through what) does the water enter and leave?
Rebar will have to be designed according to the HK structural design code
RE: Drainage manhole design
I got some of the information for the above mentions questions.
1. I've been asked to design two manhole for 3x2400mm concrete pipes. The first manhole flow is 10.585 cms. The second manhole flow is 9.981 cms.
2. It is for stormwater drain.
3. Both of the manhole are junction manholes.
What do you think 'JedClampett' suggestion?
Thanks for looking into it.
tsli
RE: Drainage manhole design
Can you share with a us a plan and a profile of the proposed arrangment.
What are your min and maximum flows through each branch? You said junction MH. So are you turning you flow directions?
What are your downstream boundary conditions? Rather into what body are you discharging?
RE: Drainage manhole design
Sure, I can share something with you. In the attached word document is the hydraulics modelling Plan&long profile. The Red line on plan is the route that for our drainage alignment. As you can see the water from North to south on plan. On the profile you will find maximum flow within the profile. That is all the information that I can provide for our discussion. The proposed manhole is place on each connection with a 35 degree of blend. Looking forward to your feed back.
tsli
RE: Drainage manhole design
Design for
- smooth transitions
- allow passage of large and small debris
- provide safe access
- check for surge pressures
- provide ventilation, perhaps grated cover
- provide divider walls which provides structural support to the ceiling and reduces turbulence
- works better with rectangular shapes than it does with circular pipes
RE: Drainage manhole design
Thank you for a engineer understand my situation. Thats why I have been ask to 'Design' Thats why is a insituate pour . That why why in the beginning I said is more like a shaft or tank. So, I will like to know did anyone got any idea or any helpful link to design it? Again, most of my experience in US is drainage. I have not done structural before.
Come on guys, help me out. Dont let the others think the PE from US can't do anything.
tsli
RE: Drainage manhole design
You can model the walls as plates using computer software or use The US Bureau of Reclamation "Shear and Moments on Flat Plates" or something like that. Start with 12 inch walls as a minimum with two layers of bars each way. Make sure all the corners and the base slab can develop the moments from the walls. Design the one largest wall and use the same reinforcing for all the walls. The top plate needs to be designed for the soil over it plus a vehicle surcharge.
Don't let anyone tell you these are easy structures. There's about a million things to think of (maybe ten) and go wrong. You need to get some "go-bys" to use as a starting point to make sure you're using good standard practice. There's a lot I didn't discuss due to lack of time and space.
RE: Drainage manhole design
RE: Drainage manhole design
RE: Drainage manhole design
tsli
RE: Drainage manhole design
http://140.194.76.129/publications/eng-manuals/
specifically, try EM 1110-2-2007, -2104, -2502 and -2902
RE: Drainage manhole design
I could not view your PDF; but, I have designed a number of custom vaults like you mention, none this large however. I typically use standard details for retaining walls to start out. I then have a structural engineer finalize the design for the top slab and pipe connections. An open junction structure is easier to maintain but not as aesthetically pleasing. I also will typically use non-shrink grout the shape the benching within the vault. The length and width of the vault is based on the minimizing hydraulic loss.
Do you have standard details available in your area? If not do a google search for DOT Standard Details in the USA. There should be quite a few.
RE: Drainage manhole design