Application of rapid impact compactor in Expressway in China

Project overview

The total length of the construction section of a highway in China is 90km, and there are many tunnels along the way. Now, taking one of the arch culverts as an example, this paper briefly analyzes the detailed application of the rapid impact compactor in the construction process of its abutment backfill project.

Engineering construction inspection and specification

(1) Mode

① First, the design elevation of backfill before compaction by rapid impact compactor shall be tested, and then the design elevation after 3 times of compaction and 6 times of compaction shall be tested respectively. Finally, the foundation settlement transformation shall be determined by comparison.

② Carry out compaction on the substrate. When the sedimentation amount of compaction at an interval of 2 times changes within 10mm, carry out on-site detection on the compactness within 1m below the pavement.

(2) Specifications

The above methods are selected for testing. When the compaction evaluation conclusion of the rapid impact compactor is 1%-3% greater than the index value, it is considered that the compaction meets the standard. Generally, all tamping points are inspected. If the inspection conclusion of tamping points does not meet the above provisions, supplementary tamping shall be carried out immediately to meet the requirements.

Test conclusion and analysis

The main parameters for the construction of this building are selected as follows: the four stroke ram of the rapid impact compactor is operated by 120cm, and the compaction is carried out in two times, each time for three times, and the high-end compaction compressive strength is selected.

Strictly implement the method checked and approved by the engineer to realize the project construction, and detect the foundation settlement transformation after the operation. The conclusions are as follows: (1) the average elevation difference of the four tamping points with a layer thickness of 80cm is 4.0cm, the maximum value is 4.2cm, and the minimum value is 3.9cm, and the distance is not significant; (2) For the four tamping points with a layer thickness of 120cm, the average elevation difference is 4.6cm, the maximum value is 4.7cm, and the minimum value is 4.5cm, and the distance is not significant; (3) The average elevation difference of the four tamping points with a layer thickness of 160cm is 5.1cm, the maximum value is 5.2cm, and the minimum value is 5.0cm, and the distance is not significant; (4) For the four tamping points with a layer thickness of 200cm, the average elevation difference is 5.6CM, the maximum value is 5.7cm, and the minimum value is 5.5cm, and the distance is not significant.

The compactness test results of the rapid impact compactor are as follows: (1) the compactness of three compaction points with a layer thickness of 80cm is increased by 2.9%, 2.3% and 2.3% respectively after compaction; (2) For the three compaction points with a layer thickness of 120cm, the compactness is increased by 2.0%, 2.0% and 2.1% respectively after compaction; (3) For the three compaction points with a layer thickness of 160cm, the compactness is increased by 1.9%, 2.0% and 2.0% respectively after compaction; (4) For the three compaction points with a layer thickness of 200cm, the compactness is increased by 2.1%, 2.0% and 2.2% respectively after compaction.

From the above detection conclusions, it can be seen that the abutment subgrade has been reasonably stiffened. According to the effective application of rapid impact compactor, it can further improve the compactness, promote the foundation settlement, ensure the overall quality, and reduce or prevent the bump at the bridge head from the source. According to the compaction test conclusion of the rapid impact compactor, there is little difference in the increase of compaction at compaction points with different layer thicknesses. According to the rationality of the equipment and the high efficiency of the work, the best ribbed layer thickness can be defined as 160cm, that is, compaction and ribbed every 160cm of backfill.