Why is the manhole cover round?

The manhole cover is not made round to prevent "a speeding car from hitting the manhole cover, taking it into the air and the manhole cover falling into the well!" If the manhole cover is thrown into the air because of every passing car. So what kind of scenery will it be in expressway? It is conceivable that no matter what shape the manhole cover is made, it is not allowed to fly into the air. The manhole cover is made into a circle because under the same caliber, the circle uses the least material and is the most economical. At the same time, circular things are also best processed and manufactured, which saves the most cost. So manhole covers are generally round.

Where can I buy manhole covers?

The installation of manhole covers requires professional technology, not just buying a manhole cover and covering it yourself.

First, you need to measure the inner diameter. This situation is at your door, you can report it to the municipal authorities.

He' nan yuxing metal products co., ltd

Difference between manhole cover and manhole cover

A manhole cover is the cover above the sewer.

There will be many underground pipelines in urban construction, such as sewers, underground gas pipelines, tap water pipelines, power pipelines, communication pipelines and national defense pipelines. These pipes should have an outlet to the ground at regular intervals. The section from the pipeline to the ground is called manhole, and the manhole is usually flush with the ground, so a cover is needed to cover the manhole. This cover is called manhole cover.

The shape difference of manhole cover:

Generally divided into round and square.

In urban road management, circular manhole covers are generally used because they are not easy to tilt and can better protect the safety of pedestrians and vehicles.

In rural areas and cable wells, they are generally square, which can better prevent rainwater and other liquids from entering.

Why is the manhole cover design round?

Because the hole under the manhole cover is round, because the cylinder can bear the pressure of the surrounding land. Moreover, there should be enough space for a person to pass through the sewer outlet hole, and the cross section of the person climbing down the ladder is basically round, so the circle naturally becomes the shape of the sewer outlet hole.

First, the same circumference, large circular area, is also the strongest for human body or tools;

Second, for the same area, the circumference of the circle is the shortest, so the pressure around the manhole cover is also great.

Third, the circle can be uniformly stressed.

Suppose that if it is made into a square manhole cover, when there is no hinge connection between the manhole cover and the wellhead, once the square manhole cover is misplaced, it is easy to fall. I think the diagonal of a square is much longer than its side, and other non-circular shapes also have this problem. Only a highly symmetrical circle can avoid this problem. The circular manhole cover can ensure that it is stuck above the wellhead and will not fall into the well, no matter it is misplaced in any direction.

Extended data:

The nature of the circle:

A circle is an axisymmetric figure, and its axis of symmetry is an arbitrary straight line passing through the center of the circle. A circle is also a central symmetric figure, and its symmetric center is the center of the circle.

The degree of the chord tangent angle is equal to half the degree of the arc it encloses.

The degree of the angle inside a circle is equal to half of the sum of the degrees of the arcs subtended by this angle.

The degree of the outer angle of a circle is equal to half the difference between the degrees of two arcs cut by this angle.

The circumference is equal, and the area of a circle is larger than that of a square, a rectangle or a triangle.

Classification of manhole covers

1. Metal manhole cover: cast iron, ductile iron, bronze manhole cover, etc.

2. High-strength steel fiber cement concrete manhole cover;

3. Regeneration of resin manhole cover;

4. Polymer-based composite manhole cover, etc.

Baidu encyclopedia-manhole cover

Why is the manhole cover round and not other shapes?

There are several reasons for choosing a circular manhole cover.

1, the circular manhole cover has the most uniform stress, which can better disperse the pressure and is not easy to cause fragmentation and collapse, so the circular manhole cover is better in terms of durability.

2. The circular manhole cover can ensure that the size of any manhole cover is not smaller than that of the wellhead, and also avoid the situation that the manhole cover falls off, and can directly cover the wellhead from any angle.

3. Because manholes sometimes need to be combed or threaded manually, the area of manholes is required to be as large as possible at this time. Among these figures, when their perimeters are equal, the circular area is the largest, and the circular shape conforms to our body shape, which is convenient for workers to go in and out.

4. The weight of the manhole cover is as high as tens of kilograms, and it needs at least a few adult men to carry it. The round manhole cover is convenient to transport and can be transported away after rolling.

The disadvantages of square manhole covers are as follows.

1, the circular manhole cover can directly cover the wellhead from any angle, and the square manhole cover can only be covered by adjusting the angle with the wellhead.

2. The diameter of the circle is only one, so the circular manhole cover will not fall into the wellhead when it rotates at will; However, the square manhole cover, whether the side length of the square or the length and width of the rectangle, must be less than the diagonal length. If the square manhole cover stands sideways at the wellhead, it is easy to fall into the wellhead.

3. The sides of a square are all composed of straight lines, and the angles formed are relatively sharp, which is easy to cause injury if it is encountered during repair or when the angles are inclined.

4. The manhole is located on the main road. Every day, when cars come and go, the wheels hit the square manhole cover, and the edges and corners are easily deformed and damaged.

Edited on 20 19-07-07

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Tell me why the manhole cover on the road is round. What's the harm if it's square?

This question was originally a test question when Microsoft recruited employees. The answer is this: any diameter of the round cover will not be smaller than the circle in which it is located, and the cover will not fall off. Any side of the square cover is shorter than the diagonal of the square circle where it is placed, but the cover will fall off when it is erected. This question is to examine a person's thinking ability from another angle. This is the figure determined after many attempts. Only the circular manhole cover can't find the diagonal, and the distance from any point to the corresponding edge is the same. As for the square, its side length is different from the diagonal length, so only the circular manhole cover is the safest when moving. Moreover, the manhole cover with the same material has the largest circular area. If it is placed at the wellhead, no matter how it is placed, the diameter between it and the wellhead is slightly smaller, so it will not fall underground, and the workers working underground are safe. Before answering this question, we should look at what is under the lid. The hole under the cover is round, because the cylinder can bear the pressure of the surrounding land best. Moreover, the manhole is to leave enough space for a person to pass, and the cross section of a person climbing down the ladder is basically round. So the circle naturally becomes the shape of the sewer access hole. The round manhole cover is just to cover the round hole. Sometimes you can see the square cover on some square holes. This kind of cover is bigger than the entrance and has rungs around it. Usually this kind of cover is made of metal and heavy. We can imagine a square hole two feet wide and a track 1 to 1.5 inches wide. In order to let the manhole cover fall in, you need to lift one end, then rotate it 30 degrees, so that it will not be blocked by the crosspiece, then make the manhole cover at a 45-degree angle with the horizon, and then shift the center of gravity enough to let the manhole cover fall. Yes, it is possible for the manhole cover to fall off, but it is very unlikely. As long as the person in charge of opening the manhole cover has a little training, he won't make such a mistake. From the engineering point of view, the shape of the manhole cover depends entirely on the shape of the hole it covers.

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Tell me why the manhole cover on the road is round. What's the harm if it's square?

Because the diameter of a circle is equal, if you make it square and let the lid stand up, it will fall in.

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Why is the manhole cover on the road round? What are the disadvantages of making a square?

The area of the lower circle with the same side length is the largest.

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Why are manhole covers all around the road? What's wrong with making it a square ...-To find the answer, just ask.

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Why is the manhole cover round? What's the difference between it and a square one?

Why is the manhole cover round?

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Why are manhole covers all round?

1, CMC is usually on the road, and people come and go every day. Attention should be paid to the safety of pedestrians when designing, and the manhole cover should not fall into the manhole. If it is designed as a triangle or a square, although the cover is larger than the manhole, it may still fall down. And if it is round, because the diameter of the circle is equal, the cover will not fall off as long as it is slightly larger. 2. Because inspection wells sometimes need manual combing or threading, the area of inspection wells is required to be as large as possible at this time. In these figures, when the perimeters are equal, the area of the circle is the largest. At the same time, the circle conforms to our body shape, which is convenient for staff to go in and out. 3. The sides of a triangle or a square are all composed of straight lines, forming an acute angle, which is easy to cause injury if encountered during maintenance. And the edge of the circle is an arc, so this problem will not appear. The reason why the cover of the sewer is round is the requirement of the structure: to bear the load from uncertain directions. Imagine that if the cover of the sewer is square or other angular shapes, when the impact load of the wheel acts on it, the angular parts are easily damaged. The manhole of the sewer is round because of the stress-the arch structure can effectively resist the earth pressure. But because the circle has the largest area in the figure with equal circumference, it uses the most materials. Therefore, from the economic point of view, some places have designed and used manhole covers with other shapes.