Precautions for Construction of Zhengzhou Concrete Manhole Covers

Cement manhole construction must strictly adhere to technical specifications, with particular emphasis on controlling the following stages:

1. Basic processing

Foundation bearing capacity must meet design requirements; soft soil layers must be replaced or compacted to avoid uneven settlement. The thickness of the foundation bedding layer must be ≥15cm, and the concrete strength must not be less than C15 to ensure flatness and compactness.

2. Well Construction Control

The prefabricated well casing must be vertically aligned for installation, sealed with a double layer of rubber rings and waterproof mortar; the cast-in-place well body formwork must be stable, with concrete layered and vibrated to prevent honeycomb and uneven surfaces. The well room's flow channel should be smoothly connected to the pipeline with a slope of ≥1%.

Pipeline joint anti-seepage

A 2cm gap is left at the pipeline and wellbore connection, filled with flexible waterproofing materials (such as water-膨胀 rubber rings), with a water-tightness test leakage rate ≤ 2m³/(24h·km).

4. Backfilling Operations Standard

Backfill with sand and gravel in layers within 50cm of the well, with each layer not exceeding 20cm in thickness, compact symmetrically to a density of ≥95%. Heavy machinery must be operated at a distance of 1m from the well body to prevent lateral pressure damage.

5. Waterproof and anti-corrosion treatment

During high groundwater levels, the exterior of the well is coated with two layers of polymer cement waterproof paint, while the interior uses impermeable concrete (P6 or above). In corrosive soil areas, an epoxy resin anti-corrosion layer is required.

6. Security Management

Hard barriers and warning lights are set up in construction areas, temporary covers or protective meshes are installed at wellheads, mandatory ventilation and gas detection are conducted before personnel enter the well, and safety ropes and supervisors are provided.