# Quarter cylinder dam gate

• cambo86
In summary, the conversation discusses how to find the force on the stopper (B) of a quarter cylinder dam gate, with a hinge at A and a stopper at B. The speaker plans to use moments around the hinge to solve for pressure forces and weight forces, but is unsure about the normal force from the ground and its positioning. They also consider if a different approach is needed and question if the gate touches the ground or only the stopper. The lecturer confirms that the reaction from the ground is zero, allowing the speaker to proceed with their solution.

#### cambo86

This is a picture of a quarter cylinder dam gate with a hinge at A and a stopper at B.
[Broken]
I need to find the force on the stopper at B as a function of the radius (R) and height of the water (h). I was going to do this by working out the moments around the hinge at A. I can solve for pressure forces and weight forces of the gate but I don't know the normal force from the ground. The hinge will have a force in the y direction so it will affect the normal force. I also don't know where to position my normal force, is it always going to be 1/2 of R or will it go through the combined centre of mass of gate and water above?

Last edited by a moderator:
Alternatively am I thinking about this problem in the wrong way and need to try a different method to find the force on the stopper?

Does the gate really touch the ground? Perhaps it only touches the stopper?

1 person
Thanks, I spoke to the lecturer today and he said that the reaction from the ground is zero.

So, can you proceed with the solution then?

Yes, I'm fine now.

## 1. What is a quarter cylinder dam gate?

A quarter cylinder dam gate is a type of floodgate or barrier used in water management systems to control the flow of water in canals, rivers, and other bodies of water. It consists of a curved gate that can be raised or lowered to regulate the water level and flow.

## 2. How does a quarter cylinder dam gate work?

A quarter cylinder dam gate works by creating a barrier in a waterway. When the gate is raised, it blocks the flow of water, causing it to pool behind the gate. This can help control the water level and prevent flooding. When the gate is lowered, the water is allowed to flow freely through the waterway.

## 3. What are the benefits of using a quarter cylinder dam gate?

A quarter cylinder dam gate offers several benefits, including flood control, water level regulation, and water flow management. It can also be used to divert water to different areas for irrigation or other purposes. Additionally, the curved design of the gate allows for more precise control over the water flow.

## 4. Are there any disadvantages to using a quarter cylinder dam gate?

One potential disadvantage of using a quarter cylinder dam gate is the cost of installation and maintenance. These gates can be expensive to install and may require regular upkeep to ensure they are functioning properly. They may also disrupt the natural flow of the waterway, which could have environmental impacts.

## 5. How is a quarter cylinder dam gate different from other types of dam gates?

A quarter cylinder dam gate is different from other types of dam gates, such as vertical lift gates or radial gates, because of its curved shape. This allows for more precise control over the water flow and can be more effective in certain situations. Additionally, quarter cylinder gates are typically smaller and can be used in narrower waterways compared to other types of gates.