Manhole refers to the facilities used for inspecting and maintaining pipelines in systems such as water supply, drainage, fire protection, electricity, and communication. Typically composed of a well shaft and a cover, they are installed at bends or junctions of pipelines, facilitating inspection and maintenance work. This article will introduce the design specifications and construction requirements for manholes.

I. Design Standards

Well Casing Design Specifications

The wellbore is the main part of the well, and its design should comply with the following specifications:

The ratio of wellbore diameter to pipeline diameter: generally should be 1.3-1.5 to ensure personnel can enter the well for maintenance and inspection.

(2) Well Depth: Determined based on pipeline layout and depth, generally ensuring that personnel can stand within the well for work.

(3) Well Casing Material and Thickness: Select appropriate materials based on the underground environment requirements, commonly using reinforced concrete. The thickness of the well casing should meet the requirements for withstanding groundwater pressure, soil pressure, and vehicle loads.

(4) Well Bore Entrances and Exits: The well bore should be equipped with entrances and exits for easy access by personnel for inspection and maintenance.

2. Manhole Cover Design Standards

Manhole covers are the lids of manholes, and their design should comply with the following specifications:

(1) Material and thickness of manhole covers: Generally, gray cast iron is used for the material, and its thickness should meet the requirements for bearing pedestrian, vehicle, or other loads.

(2) Manhole Cover Dimensions: The size of the manhole cover is determined based on the diameter of the well shaft, ensuring that it completely covers the well and is level with the ground to prevent tripping hazards for pedestrians or vehicle damage.

(3) Slip-Resistant Design for Manhole Covers: Manhole covers should possess certain slip-resistant properties to prevent pedestrians from slipping on wet surfaces.

3. Additional Design Standards

(1) Ventilation and Drainage Design: To ensure proper air circulation within the well, a ventilation hole can be installed at the top of the well shaft to supply fresh air adequately. Additionally, a drainage hole should be set at the bottom of the well to prevent any accumulation of water.

(2) Signage Design: Signs should be placed on manhole covers, including information such as the type of cover and the well's identification number, for quick recognition and location.