Manholes are plastic structures, either injection-molded from one piece or brick-built, used within building districts (residential, public buildings, industrial areas, etc.) for buried plastic drainage pipelines with an external diameter not exceeding 800mm and a burial depth not exceeding 6m. They are typically located at junctions, bends, changes in pipe diameter or slope, and drop-offs, designed for easy periodic inspection, cleaning, unblocking, or well entry operations.
The plastic integral injection molded manhole is characterized by its main manhole base, which is formed through a single injection molding process. The well shaft has a 360-degree annular bearing platform, and the well body and base are reinforced with a mesh of ribs. Each joint features an annular reinforcement design. Depending on the number and angle of the connections, there are starting manholes, straight-through manholes, 45-degree bend manholes, tee manholes, and four-way manholes, among others. To accommodate various drainage conditions, the plastic manhole is also equipped with accessories such as variable diameter connectors, confluence connectors, and multi-joint well shafts, all of which are integral injection molded to ensure the smooth flow and密封ity of the entire drainage system.
We are installing asphalt concrete on top of cement concrete roadways and setting up inspection wells. Typically, the process involves first removing the original pavement, raising the inspection well casing, and then once the asphalt concrete paving has set, cutting the surrounding area into a hexagonal shape and removing excess material. After installing the inspection well, we pave asphalt concrete within the hexagonal area.
2. Install asphalt concrete on top of existing asphalt pavements and inspect manholes. Typically, this involves removing the original pavement, raising the manhole shaft, or leaving an empty space at the original manhole location. Once the asphalt concrete pavement is laid and shaped, the surrounding area of the manhole is cut into a hexagonal shape, excess material is chiseled away, or a manhole is installed within a pre-set hexagonal or circular space, followed by laying asphalt concrete within the hexagonal or circular area.
3. The installation of asphalt concrete and inspection wells is underway on the newly constructed subgrade. Generally, temporary inspection wells are installed, and after the entire asphalt concrete road surface is completed, the wells are cut into hexagons around them or installed in pre-reserved circular voids after excess materials are cleared.
After installing the manholes using the aforementioned methods, the surrounding foundation treatment of the manhole shaft is a weak link. Moreover, the asphalt pavement around the manholes was laid a second time, often resulting in poor compaction. Over time, this can lead to sinking of the asphalt pavement around the manholes, creating concave "belly button" shapes, which affects the smoothness and aesthetics of the road surface, particularly impacting vehicle comfort. Additionally, when using mechanical paving, the temporary installation of the manholes affects the paving and compaction operations.
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