Why are the entrances and exits of the sewers and the lids round?

Because the hole under the lid is round, the cylindrical shape best withstands the pressure of the surrounding land. Moreover, sewer access holes meant that there was enough space for one person to pass through, and the cross-section of a person climbing down a ladder was basically round. So the round shape naturally becomes the shape of the sewer access hole.

The round manhole cover is only to cover the circular opening.

There are several reasons why the lid of the sewer is round:

1. The wellhead can be directly covered from any angle. The square must be adjusted to the same angle as the wellhead; The diameter of the circular manhole cover is equal in length, and it can be matched no matter how it rotates, and it will not fall down due to the side length not being as long as the diagonal.

2. The diameter of the circle is only one, so the circular manhole cover will not fall into the wellhead if it rotates arbitrarily on the wellhead. The square manhole cover, whether it is the side length of the square or the length or width of the rectangle, is necessarily less than the length of the diagonal, if the square manhole cover stands on the side of the wellhead, it is easy to fall into the wellhead.

3. The round shape can be rolled, easy to transport, and can be rolled.

4. Save materials, use less materials for the same large area.

5. The sewer mouth is round, which can reduce the probability of irregular objects (bicycles, stones, etc.) falling after the sewer cover is stolen.

Standards for manhole covers in China:

There are many kinds of national standards for manhole covers in China, single-layer, double-layer, cast iron, ductile iron, composite, cement, magnesite and so on.

According to the latest national standard GB T 23858-2009 latest standard requirements.

The manhole cover load capacity can be divided into the following types:

One of the points to note is that the manhole cover load capacity and the ability of the manhole cover to pass through the vehicle are not the same concept.

The manhole cover load capacity refers to the pressure test carried out by a pressure testing machine within the unit area, usually weighing 40 tons. In the case of a passing vehicle, the calculation formula for a 5-axle heavy-duty truck is: 5 axles x 40 tons = 200 tons.

With a gross weight of 200t tonnage, this heavy-duty manhole cover can be guaranteed to pass.

The above content reference: Encyclopedia - manhole cover.

The entrance and exit manhole cover of the sewer is round, mainly because of its safety and cost savings. The circular diameter is fixed, with fixed width, when the round manhole cover is placed at the wellhead, it will not fall down no matter how it is placed. And the circular force is uniform, can bear the load from the uncertain direction, when the wheel presses, the manhole cover is still flat.

According to the material, the manhole cover can be divided into metal manhole cover, high-strength fiber cement concrete manhole cover, resin manhole cover, etc. It is generally round. It can be used for green belts, sidewalks, motorized lanes, docks, alleys, etc.

1. The sewer pipe is round pipe, and the entrance and exit are round and well connected. 2. The entrance and exit are round, and the lid is also round, which is easy to make, and easy to make with it. 3. The diameter of the round cover is the same in all directions, and it cannot fall into the hole to ensure the safety of installation and use.

Because the diameter of the perfect circle is equal from any point of the arc through the center of the circle to the other point of the arc, if the lid is opened and closed in any direction, the lid will not fall into the sewer.

Because all the diameters of the circle are equal, the lid of the round shape will not fall anyway, but the large diameter of the oval is greater than the small diameter, and the diagonal of the rectangle is greater than the height, and it is possible to fall. Because the diameter of the circle is equal regardless of that.

The force is evenly applied to the circle, and the round shape of the nozzle and the lid will be relatively stable.

2.When the circular manhole cover is stressed, the pressure spreads to the surroundings. Due to the uniform diffusion, it is not easy to break and collapse.

3.The round cover can save materials, increase the coverage area of the hole, and increase the strength of the manhole cover and the well seat is not easy to be crushed;

4.Easy to transport, round lids can roll directly on the ground, while square or triangular lids cannot;

5.The round manhole cover is not easy to tilt, which can better protect pedestrians and driving safety.

Indeed, for this reason, the circumference of the circle is larger than that of other shapes, so there is less material to be used, because your perimeter is built with material (cement).

The shape of the entrance and exit of the sewer and the cover is round reason:

1. The manhole is located on the main road, and people walk every day, so it is necessary to pay attention to the safety of pedestrians when designing, and the cover can not fall into the manhole. If it is designed as a triangle or square, although the Gaier is larger than the manhole mouth, there is still a possibility of falling. And if it is round, since the diameter of the circle is equal, as long as the lid is a little larger, it will not fall.

2. Because the manhole sometimes needs to be manually carded or wired, etc., the area of the manhole is required to be as large as possible. In these figures, when their circumferences are equal, the circle has the largest area. At the same time, the round shape is in line with the human body, which is convenient for the staff to enter and exit.

3. The side of the triangle or square is composed of straight line segments, and the corners are sharp, which can easily cause injury if touched during repair. The edge of the circle is an arc, so this problem does not occur.

In the 70s of the 20th century, many Japanese people suffered from the noise of manhole covers, and asked the local government to solve the "noisy manhole covers". Japan** immediately revised the standard of sewer manhole covers, changed the cylindrical manhole cover to a conical manhole cover with a large top and a small bottom, and required that the manhole cover casting must be accurate to the millimeter.

In this way, the manhole cover and the road surface can be fitted seamlessly, which not only eliminates noise, but also increases the difficulty of stealing the manhole cover. In Japan, most sewer manhole covers are uniquely numbered and incorporated into the sewer management system. On the one hand, damaged manhole covers can be quickly identified, and on the other hand, it is possible to know when the manhole cover has reached the end of its life and should be repaired and replaced.

Why is the mouth of the test tube round? The reason is similar to this, in order to get into the water faster, and the round one looks more comfortable than the angular one.

The round lid doesn't fall inside.

It is convenient for workers to enter and exit, and it is not easy to get stuck things.

Hello, the shape of the sewer entrance and exit and the cover is circular for the following reasons: 1. From a mathematical point of view, the same circumference, the largest area is circular 2. From the perspective of making the suffocation use Shiqing, the circular manhole cover is not easy to tilt, which can better protect the safety of pedestrians and vehicles. 3. Among our common items, the round big ant brother iron cover is rare, so the scrap station will also pay attention to it when acquiring, and the square iron plate is everywhere, so the round shape can be anti-theft.

1. The side of the triangle or square with high safety is composed of straight line segments, and the corners are sharp, which can easily cause injury if it is touched during repair. The edge of the circle is an arc, so this problem does not occur. The reason why the cover of the sewer is round is the requirement of the structural force:

In order to withstand loads from uncertain directions. If the cover of the sewer is square or has other angular shapes, when the impact load of the wheels acts on it, the edges and corners of the sail are easily damaged. The reason why the inspection well of the sewer is made round is also due to the consideration of force.

2. It is convenient to repair because the manhole sometimes needs to be manually dredged or wired, etc., and the area of the manhole is required to be as large as possible. In these figures, when their circumferences are equal, the area of the circle is the largest. At the same time, the round shape fits our body shape, making it easy for staff to get in and out.