Lets try this again. lol.
Assume, theoretically, that a deep, precast concrete manhole with a water tight lid is designed based on all standard methods and criteria (following DD-41: http://www.concretepipe.org/wp-content/uploads/2014/09/DD_41.pdf). A lower lip on the base is even added to be...
CVG, I agree with your analysis. The situation I'm exploring would have water tight lids. These are good to about 20 psi. Failure of a joint would be slow and rare.
Again, this is a mental exercise and exploration..
I created a little model: https://youtu.be/IM0gyPWD1jE
Bimr, I am using standard methodology and have no objections to it at all, I am just curious as to how the forces are acting on the structure in various "theoretical" situations. Everyone mentions buoyancy forces, but all I am asking is if a structure has no bottom (say, due to a joint failure...
Thanks for the responses guys.
I am over thinking things...as an engineer its my job! And its also a fun thought experiment. I don't ever just *accept* what I am told without fully understanding to the best of my ability. My questions dont apply to basic design and installation principles, Im...
After much exploration and even building a scale proof of concept model, I have made some conclusions.
The important key here is the joints of the precast sections should be water tight as necessary for the depth (about 15 PSI for a 35' deep submerged manhole excluding air pressure). If the...
I am specifying some relatively deep 5' diameter precast concrete manholes (25'-35' deep) which are located in a floodplain (will be fully submerged during floods) and thus they will have water tight lids with MH rims at existing ground level. I have ran the standard buoyancy calculations and...