For soft soil foundation, when the bottom of the trough is lower than the groundwater level, it is advisable to pave a layer with a thickness of not less than 0. 15m and gravel particles of 5mm~? 40m？ The thickness of the upper sand cushion (medium coarse sand) shall not be less than 0.05m? The total thickness of cushion is not less than 0.2m
2. After slotting, the operation items such as slot width, thickness of foundation cushion, elevation of foundation surface, whether the drainage ditch is unblocked, whether there is silt and debris in the ditch, and foundation settlement disturbance shall be inspected and accepted respectively, and arrangements can be made only after they are qualified.
3. Generally, it is stipulated that the pipeline shall be laid on the undisturbed soil foundation or on the stratum that is backfilled and compacted after grooving, and the thickness of the covering soil at the top of the pipeline shall not be less than 0.7m below the roadway.
4. Pipes shall be laid in a straight line. When flexible interfaces need to be laid in broken lines, the relative rotation angle of each socket of the pipeline should generally not be greater than 65438 0.5.
Extended data:
HDPE double-wall corrugated pipe foundation;
Pipelines shall be based on soil arc. For ordinary soil, a layer of medium-coarse sand foundation with a thickness of 100mm should be laid on the undisturbed soil foundation below the pipe bottom or on the basis of backfill compaction.
When the soil quality of local foundation is poor, gravel base with cushion thickness not less than 200mm can be used, or it can be laid in two layers. The lower layer is gravel with a particle size of 5~32, with a thickness of 100~ 150mm, and the upper layer is medium-coarse sand not less than 50mm.
For soft soil foundation, when the bearing capacity of the foundation is less than the design requirements or the undisturbed soil of the foundation is disturbed, the foundation must be strengthened first, and then the medium-coarse sand foundation layer is laid.
At the shaft angle within the azimuth range of the soil arc foundation designed for the pipeline, it must be backfilled and compacted with medium coarse sand or gravel soil. Backfill range shall not be less than azimuth 2a plus 30.
The groove at the socket joint in the pipeline foundation should be dug when laying the pipeline, and the length, width and depth of the groove can be determined according to the size of the pipeline joint. After the joint is completed, it should be backfilled and compacted with medium coarse sand immediately.
For the sections where the longitudinal uneven settlement of the pipeline may occur due to factors such as pipeline load and soil change at the bottom, the foundation should be strengthened before the pipeline is laid.
References:
Code for Construction of HDPE Double-wall Bellows-China Agricultural News Network