Shapes of surface drains

The following are the four shapes, which are commonly adopted in the construction of surface drains.

1. Rectangular surface drains
2. Semi-circular surface drains
3. U-shaped surface drains
4. V-shaped surface drains

1. Rectangular surface drains

Heavy discharge can be carried by these drains. However, when the depth of flow is shallow, they do not achieve the necessary velocity and easily deposit.

2. Semi-circular surface drains

These are appropriate for streets with a small amount of discharge that needs to be accommodated. These drains are prefabricated, semi-circular portions of asbestos cement, stoneware, or concrete pipes.

3. U-shaped surface drains

These drains are easy to construct and they combine the advantages of semi-circular drains and rectangular surface drains.

4. V-shaped surface drain

These drains are more effective hydraulically, but they are challenging to build. These drains will be constructed with fluctuating. These drains may generate a good velocity and can transport a variable discharge without depositing solids everywhere. These drains are built using cement mortar for stone or brick construction. Rich cement mortar has been used to neatly plaster the inside surface. In order to prevent either silting or scouring, the drains are equipped with adequate slopes that keep the velocity within the range.

DIFFERENT SHAPES OF CROSS-SECTIONS FOR SEWERS CIRCULAR AND NON CIRCULAR

Because of the following factors, circular sewers are typically used.

1. Construction costs for the same area of a circular form are lowest since it has the smallest perimeter.
2. Lack of corners minimises the deposition of organic materials.
3. They are simple to produce, assemble, and handle.
4. Because of their circular design, these are subject to hoop compression, requiring only a small amount of concrete and no reinforcing.
5. Because they offer the greatest hydraulic mean depth while running full or half full, they have exceptional hydraulic properties.

When the discharge does not vary significantly and there is less likelihood of sewers flowing at very shallow depths (less than half), circular sewers perform well. However, there are a few additional uses for sewers with non-circular geometries.

1. To decrease building costs
2. To increase flow velocity when sewage is present at shallow depths
3. To ensure greater structural stability
4. To streamline the construction procedure
5. Enlarge them to allow a man to enter for maintenance or cleaning