Hydraulic Capacity of Back pitched pipes
Hydraulic Capacity of Back pitched pipes
(OP)
I am working on determining the carrying capacity of an old brick storm sewer system. Some of the segments in the system have sagged over the years resulting back pitched pipe runs. Manning formula does not work with negative slopes. Any ideas?





RE: Hydraulic Capacity of Back pitched pipes
good luck
RE: Hydraulic Capacity of Back pitched pipes
RE: Hydraulic Capacity of Back pitched pipes
http://dnr.metrokc.gov/wlr/dss/kcrts.htm#kcbw
RE: Hydraulic Capacity of Back pitched pipes
RE: Hydraulic Capacity of Back pitched pipes
Gravity flow is pushed by the difference in total energy, so what will happen here is that the flow will build up a head to push the flow through the pipe. This will happen even when the pipe is not flowing full. HEC-RAS can model this using a bridge or culvert routing in short increments (but it's tricky).
The other way of doing this is by hand, using the standard step method. This may be faster than a computer program for short segments, for one discharge.
Leo Sanchez
www.sanchezengineering.ca