Pipes should be laid in a straight line. When flexible interfaces need to be laid with dotted lines, the angle of each socket of the pipeline should generally not be greater than 1.5.
The drainage pipeline project can be constructed in the same tank, but it must comply with the relevant provisions on the design and construction of shared drainage pipelines in the same tank.
When the pipeline crosses railways, high-grade embankments and structures with obstacles, a protective sleeve made of reinforced concrete, steel, cast iron and other materials should be set, and the inner diameter of the sleeve should be more than 200mm larger than the outer diameter of the corrugated pipe, and the end space between the pipeline and the sleeve should be filled with fillers.
When the buried depth of pipeline foundation is lower than the bottom surface of building (structure) foundation, the pipeline shall not be laid in the compression zone of foundation diffusion angle below the foundation surface.
In areas where the underground water level is higher than the bottom elevation of the excavated trench, measures should be taken to reduce the water level during construction to prevent the trench from becoming unstable.
Installation can only be carried out when the underground water level drops to 300 mm ~ 500 mm below the lowest point of the tank bottom. During backfilling, the water level shall not stop.
1, groove
The clear width of the bottom of the trough should be determined according to the outside diameter of the pipeline plus 600 mm ~ 1000 mm, so as to facilitate manual operation at the bottom of the trough.
When excavating the trench, the height of the basement should be strictly controlled and the surface of the basement should not be disturbed. Undisturbed soil of 200 mm ~ 300 mm above the design elevation of the basement shall be retained and manually cleaned up to the design elevation before laying. In case of local overbreak or disturbance, backfilling is not required, but 10 mm ~ 15 mm natural graded sand or medium coarse sand can be replaced, leveled and compacted.
During construction in rainy season, the slotting length should be shortened as much as possible to realize quick slotting and backfilling, and measures should be taken to prevent bubble slots. Once the bubble tank appears, the accumulated water should be removed, the softened soil layer affected by bubbles should be removed, sand and gravel materials or medium-coarse sand should be replaced, and foundation treatment should be done well.
When slotting manually, the mixed soil at the upper part of the slot and the good soil at the lower part of the slot should be stacked separately for backfilling. Pile soil shall not affect the stability of the pipe trench. When there are hard-to-remove stones, crushed stones, bricks and other substances buried in the bottom of the tank, they should be removed to 200mm above the design elevation, and then paved with natural and mixed sand and gravel, and the surface layer is paved with sand and soil for leveling and compaction. The tank bottom should not be soaked or frozen.
2. Foundation
Cushion foundation is adopted in the design of pipeline foundation. For general soil areas, the basement only needs to be paved with a layer of sand cushion with a thickness of100 mm; ; For soft soil foundation, when the bottom of the trough is lower than the groundwater level, it is advisable to spread a layer of gravel or gravel with a thickness of 150mm, and the gravel particles are 5 mm ~ 40 mm The thickness of sand cushion (medium coarse sand) on it is not less than 50mm, and the total thickness of cushion is not less than 200 mm
After slotting, the work items such as slot width, thickness of foundation cushion, elevation of foundation surface, whether the drainage ditch is unblocked, whether there is silt and sundries in the ditch and whether there is disturbance at the grass-roots level shall be inspected and accepted respectively, and arrangements can be made only after they are qualified.
3, pipeline installation
Pipeline installation generally adopts manual installation. During installation, lift both ends of the pipeline to the construction personnel at the bottom of the tank. Open-cut pipes with groove depth greater than 3m or pipe diameter greater than 400mm can be laid with nonmetallic ropes, and then stabilized with theodolite.
When installing the interface, first confirm the placement position of the rubber ring and the depth of the socket, then clean the inner wall of the socket and apply lubricant. For pipes with sockets, the insertion direction of sockets is generally consistent with the direction of water flow, and they are installed from low to high. When inserting the socket, a wooden baffle with small diameter (nominal diameter < < 400mm= =) can be set at the pipe end manually, and the installed pipe is slowly inserted into the socket along the aligned axis with a crowbar, and gradually installed. For large-diameter (nominal diameter > > 400mm) pipelines, cables can be used to bind the pipelines, and then two rope tighteners (or winches) and other tools can be used to tighten the pipelines symmetrically and evenly. After the nozzle is docked, recheck the elevation and central axis of the pipeline. For pipes connected by sleeve connectors, one end can be installed at a flat place on the groove first, and then the pipe can be slid into the groove for installation. The specific method is the same as above.
4. Connection of pipelines and inspection wells
When pipes are connected with inspection wells, flexible interfaces or sockets should be adopted for connection; When the requirements are not high, it can also be directly inserted into the inspection well wall. In order to ensure that the pipeline or pipe fittings are well combined with the manhole wall without water leakage, the structure of precast concrete outer ring and rubber ring can be used for the connection between the pipeline and the manhole.
5, pipeline repair
After the pipeline was laid, the pipeline wall was partially damaged due to unpredictable factors. When the length or width of the damaged part does not exceed the pipe circumference112, the repair measures of Haval parts can be taken. If the damaged hole is less than 100mm, you can cover the damaged part with one-piece rubber ring first, then install Haval parts and tighten the bolts evenly.
6, backfill requirements
After the pipeline is installed and accepted, it should be backfilled immediately, at least to the height of twice the pipe diameter at the top of the pipe.
Trench backfilling shall start from the bottom foundation of the pipe and be manually backfilled to 0.5m above the top of the pipe. It is forbidden to backfill with mechanical bulldozing.
Mechanical backfill can be used for the part above 0.5m at the top of the pipe, and it can be compacted or rolled simultaneously from both sides of the pipe axis.
During backfilling, there shall be no water in the ditch, no water, soil and organic matter shall be used for backfilling, and the backfill shall not contain hard objects such as stones, bricks and frozen soil blocks. Trench backfilling,
Backfilling shall be carried out symmetrically from both sides of pipelines, inspection wells and other structures at the same time, so as to ensure that the pipelines and structures will not be displaced, and limit measures can be taken when necessary.