Where: h= ditch depth, calculated according to the design pipe bottom elevation.

B= width of trench bottom.

L= trench length.

0.3= grading coefficient.

Extended data:

Construction method

Earthwork excavation construction, including loosening soil, crushing, digging and loading, transporting slag and other processes. Rock excavation, in addition to the soft rock can be shoveled by scarifier, generally need to use blasting to loosen and break.

Manual and semi-mechanized excavation, using simple tools, such as shovel picks, pneumatic picks, pneumatic drills, etc. Combined with lifting or simple small transportation tools, it is suitable for small water conservancy projects. Some irrigation and drainage ditches are directly constructed by ditching machines and can be formed at one time. Earthwork excavation of large and medium-sized water conservancy projects is mostly done by machinery.

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