Installation of precast concrete manholes
1. Construction preparation
1.1The characteristic value of the foundation bearing capacity of precast concrete inspection wells is not less than 100KN/m2
1.2When assembling the precast concrete inspection well, suitable cranes and lifting equipment should be selected according to the weight and radius of rotation of the inspection well components.
1.3A 100mm gravel layer is laid under the precast concrete inspection shaft chamber.
1.4Prepare cement mortar or polyurethane cement mortar with a ratio of 1:2.
1.5The length of various pipes connected to the precast concrete inspection well chamber should not exceed 1000mm.
2. Joint processing
When rigid connection is used, the contact surface between the precast concrete inspection well and the pipe interface should be "chiseled". When connecting, 1:2 cement mortar or polyurethane cement mortar can be used for caulking, and the joint thickness is 10mm-15mm. The inner joints of the interface are hooked and flattened with original mortar to ensure full mortar.
When using flexible rubber rings to connect reinforced concrete pipes, the rubber rings should be installed in place and ensure the sealing of the interface.
After the inspection well and pipeline are installed in place, the backfill around the well and around the pipeline should be backfilled at the same time. The density of the backfill should be determined according to the road surface requirements, and usually should not be less than 95%. When the inspection well is within the frozen soil range, non-frost heaving soil with a width of at least 300mm should be backfilled around the well and pipes.
When the foundation of branch and main pipes falls into the well chamber chute, the chute needs to be processed. The specific method is: fill it with concrete, graded sand and gravel or other soil materials without capillary water absorption properties, and control the compaction density. The compaction coefficient should not be less than 97%.
The construction, installation and acceptance of precast concrete inspection wells should comply with GB50204 "Concrete Structure Engineering Construction Quality Acceptance Regulations"
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