(1) When open ditch is used for drainage, the drainage ditch shall be kept unblocked without water in the trench. When well point dewatering is used, the dynamic water level shall be kept below the bottom of the trench no less than 500mm<> (2) The backfill shall be filled to a sufficient degree to prevent the pipeline from floating due to water recharge outside the trench. (3) The backfill soil on both sides of the pipeline and within 500mm above the top of the pipeline shall not contain gravel, bricks, frozen soil and other miscellaneous hard objects. (4) The backfill soil shall be tamped in layers. The thickness of each layer is shown in Table 1. The compaction tools shall be paved with wood rammer, iron rammer 20 frog rammer and fire rammer 20-50 pressure.
What are the standards when the pipeline is laid and backfilled?
(1) when using open ditch drainage, the drainage ditch should be kept unblocked, and there should be no water in the trench. when using well point dewatering, the dynamic water level should be kept below the bottom of the trench not less than 500mm <>
(2) The backfill shall be filled to a sufficient height to prevent the water from being recharged outside the tank and causing the pipeline to float.
(3) The backfill soil on both sides of the pipeline and within 500mm above the top of the pipeline shall not contain gravel, bricks, frozen soil and other miscellaneous hard objects.
(4) The backfill soil shall be compacted in layers. See Table 1 for the thickness of each layer.
Wood rammer, iron rammer Yun 20 frog rammer, fire rammer 20-50 roller 20_30 vibrating roller Yun 40
(5) The backfilling time should be at the lowest temperature in a day and night. The backfilling must be backfilled from both sides of the pipe at the same time, and the second layer shall be backfilled after compaction until the backfilling reaches 500mm above the top of the pipe. The trench support shall be removed in sequence according to the backfilling order under the condition of ensuring the construction safety. After the vertical sheet pile is removed, the gap shall be filled with sand;
(6) Before the pipeline pressure test, under normal circumstances, the backfilling height above the top of the pipe should not be less than 500vmm, and 200mm of the pipe joint should be reserved for backfilling.
(7) Large area backfilling after the pipeline pressure test is qualified should be carried out when the pipeline is full of water. After laying, the pipeline should not be in empty state for a long time. A small amount of stones with a diameter of not more than 100mm are allowed in the backfill soil on the 500mm part above the pipe top, and mechanical backfilling is used, and the machinery is not allowed to run above the pipe.