What is the filling method of rock-filled subgrade construction?
1, vertical filling method (dumping method)
It is mainly used for the second-class and lower-grade pavements, especially the roads that are difficult to be constructed on steep slopes or excavated by a large number of blasting, and the rock-filled embankments that cannot be filled in layers from bottom to top, steep slopes, gravel, swamp areas and water. There are many problems in compaction and stability of subgrade constructed by this method.
2, layered compaction method (rolling method)
This is a widely used method to ensure the quality of rock-filled embankment. This method is layered horizontally from bottom to top, filled and compacted layer by layer. This method is used for stone-filled embankments of expressways, first-class highways and other highways with higher pavement grades. Rock-filled embankment divides the filled road section into four construction steps, four operation sections and eight technological processes for layered construction.
The fourth-level construction steps are: below subgrade surface 1 step, the second step below 0.5- 1.5m, the third step below 1.5-3.0m, and the fourth step below 3.0m. These four operation sections are: rock filling section, leveling section, rolling section and inspection section. During the construction, the filling and excavation operation face is stepped, and the step distance depends on the specific situation and the adaptation to mechanized operation. The general length is about100m m, and the stone filling operation starts from the lowest point and is filled horizontally in layers. For each layer, the main aggregate is laid mechanically, and the joint filling material is spread in leveling operation. The stone filling gap shall be filled with pebbles or chips, and rolled by heavy vibratory roller until the pebbles on the top surface of the filling layer are stable.
The eight technological processes of stone embankment filling are: construction preparation, packing shipment, layered filling, paving and leveling, vibration rolling, detection and signature, subgrade forming and subgrade renovation.
3. Impact compaction method
Impact the roadbed filler periodically, with large amplitude and low frequency by impact roller of impact compactor, and compact the filler; Dynamic compaction method is to use a crane to lift a differential hammer to fall freely from a height, and use strong dynamic impact to force the displacement of rock and soil particles, thus improving the compactness of the filling layer and the strength of the foundation.
4. Dynamic compaction method
The layered dynamic compaction construction of rock filling requires layered filling and dynamic compaction to cross, and the loose paving coefficient of each layer thickness of the first layer is 1.2, and subsequent layers can be adjusted according to the actual situation of the first layer. Each layer is compacted and tamped continuously, and a rammed pit is formed after being exhausted, and the rammed pit is filled with the same type of stone filler. Because the layered thickness is 4-5m, the filling method is adopted for filling operation, and the large loader and dump truck must cooperate with each other for shipment. Paving must be done by a large crawler bulldozer, and the backfill of rammed pit must also be done by a bulldozer. The main tamping and full tamping of each layer and surface layer shall be carried out by cranes and rammers, and the subgrade surface must be finally compacted and leveled by vibratory rollers.
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