下水道井盖为什么是圆的？Why is the sewer manhole cover round?

对于下水道井盖为什么是圆的这个问题，想必大家都很困惑，为什么不是其他形状的呢？

I think everyone is very confused about why the sewer manhole covers are round. Why are they not in other shapes?

以下有一些可能是你听过的传闻：

Here are some rumors you may have heard:

传闻1：国外有位哈佛教授问一位学生，下水道井盖为什么是圆的？学生则回答说：“圆的东西东西更容易滚到合适的位置上去”。对于学生的回答，教授则说：“这个答案虽然不对，但是猜的也不算错”。

Rumor 1: A Harvard professor from abroad asked a student why the sewer manhole cover is round? The student replied: "Round things are easier to roll to the right position." For the student's answer, the professor said: "Although this answer is wrong, the guess is not wrong."

传闻2：下水道井盖为什么是圆的？有人说：纯粹是为了节约原材料，其实方形的下水道井盖也有不少，但是总数还是圆形的多。

Rumor 2: Why is the sewer manhole cover round? Some people say: It is purely to save raw materials. In fact, there are many square sewer manhole covers, but the total number is still more round.

传闻3：听说是为了美观，因为生产工艺，圆形的下水道井盖也更为容易生产。

Rumor 3: I heard that it is for aesthetics. Because of the production process, the circular sewer manhole cover is also easier to produce.

下水道井盖为什么是圆的

根据以上传闻及原因分析，感觉还是有一定的道理，但是根据专业科学角度来讲，对于下水道井盖为什么是圆的根本原因还是有一定的差别，具体分析如下：

According to the rumors and analysis of the reasons, I still feel that there is some truth, but from the perspective of professional science, there are still certain differences in the root cause of why the sewer manhole covers are round. The specific analysis is as follows:

现在市政建设当中，不论是什么材质的下水道井盖，基本都分为圆形和方形两种。在路政设施下，基本都是采用圆形结构的下水道井盖，因为圆形的下水道井盖所有直径长度相同，如果发生意外情况，如被车辆压碎边角或被轧起，根据其下水井盖的直径长度绝对不会掉入窨井中，可以更好的保障行人车辆安全。

In the current municipal construction, no matter what material the sewer manhole covers are, they are basically divided into two types: round and square. Under road administration facilities, the circular structure of the sewer manhole cover is basically adopted, because the circular sewer manhole cover has the same diameter and length. If an accident occurs, such as being crushed by a vehicle or rolled up, according to the diameter of the manhole cover The length will never fall into the manhole, which can better protect the safety of pedestrians and vehicles.

而如果采用方形的下水道井盖，如果发生意外破损情况，则极易掉入窨井，造成安全隐患。当然有人会说，如果把方形井盖口设计的更小，把下水道井盖设计的大一些，那肯定也不会掉下去啊，的确，就如传闻2中说道，下水道井盖为什么是圆的，很大一部分原因的确是为了节约生产成本。

And if a square sewer manhole cover is used, if accidental damage occurs, it will easily fall into the manhole, causing safety hazards. Of course, some people will say that if the square manhole cover is designed to be smaller and the sewer manhole cover is designed to be larger, it will definitely not fall. Indeed, as said in Rumor 2, why the sewer manhole cover is round and large Part of the reason is indeed to save production costs.

比如，现在的下水道井盖总共有水泥下水道井盖（主要由井盖塑料模具预制而来）、铸铁下水道井盖、玻璃钢下水道井盖以及一些复合材料制成的下水道井盖，一个两个可能对于节省生产原料的效果一般，但是实际只要稍微了解一下每个城市的下水道布置，你就会发现，采用圆形的下水道井盖对于节省生产成本及地球资源的帮助是相当大的，所以，以上几点才是下水道井盖为什么是圆的地真正原因。

For example, the current sewer manhole covers have a total of cement sewer manhole covers (mainly prefabricated by plastic concrete molds for manhole covers), cast iron sewer manhole covers, FRP sewer manhole covers, and some composite material sewer manhole covers. One or two may have a general effect on saving production raw materials. , But in fact, as long as you have a little understanding of the sewer layout in each city, you will find that the use of circular sewer manhole covers is quite helpful in saving production costs and earth resources. Therefore, the above points are why the sewer manhole covers are The real reason for the round.