| 摘要 |
Backfill soil is compacted under the haunches of and up to the spring line of a pipe laid in a trench by tamping the soil in two directions with two pairs of hydraulically-operated ram plates extending from an elongate frame which is supported and moved by wheels along the pipe. The first pair of ram plates, located near the bottom half of the pipe, compact the soil under the haunch of the pipe by compacting the soil at an angle such as 45 DEG (from vertical) from either side of the pipe towards the centerline of the pipe. The second pair of ram plates, located behind the machine and above the spring line of the pipe, compacts the soil in a downward (vertical) direction on either side of the pipe.
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