Why the manhole cover and the round bucket lid are round
1. The well is located on the road . People who walk every day come and go . When designing, pay attention to the safety of pedestrians . The cover cannot fall into the well . If it is designed as a triangle or a square , thecover is bigger than the well . but it is possible to fall in. and if it is round, because the equivalent diameter of the circle, so long as Gail little freshman, would not fall.
2 , because the well sometimes needs manual combing or wire laying, etc. , this time requires the area of the well to be as large as possible . In these figures , when their circumference is equal , the area of the circle is the largest . At the same time, the circle is in line with us. size, easy in and out staff.
3 , the triangle or the square edge consists of straight line segments , the angle formed is sharp , if it is easy to make people hurt when repairing . The round side is an arc , this problem will not occur . The sewer the reason why the cover is round, the force requirements for the structure:
In order to withstand the load from the uncertain direction. Imagine if a manhole cover with a square or other angular shapes, when there is a wheel on which the impact load, very easy to damage the dihedral angle region. The reason why the sewer manhole made Round , also for force considerations - arched structure can effectively resist earth pressure
However , because the area of the circle is the largest in the pattern with the same circumference , the material used is the most . Therefore , from the economic point of view , some shapes have been designed to use the manhole cover of other shapes .
