Silt, swamp soil, peat soil, frozen soil, organic soil and domestic garbage soil are not suitable for subgrade filling.

Silt, muddy soil and general clay with low natural strength, high compressibility and low water permeability are collectively called soft soil. The main failure forms of soft soil subgrade are subgrade cracking and failure caused by excessive settlement. Under the action of heavy load, the foundation is prone to overall shear, local shear or breakthrough failure, resulting in pavement settlement and subgrade instability; Due to the overload of pore water pressure (too late to dissipate) and excessive shear deformation, subgrade slope will be unstable.

There are dozens of construction methods for soft soil foundation treatment, and the common treatment methods include surface treatment, replacement, dynamic compaction and vertical drainage consolidation. Specific treatment measures can be taken, such as soil replacement, riprap and silt squeezing, sand cushion replacement and filling, back pressure berm, sand pile, powder jet grouting pile, plastic drainage board, geotextile and so on.

When the subgrade pressure is measured formally, the test section should be done when conditions permit to obtain the relevant technical parameters of subgrade or base construction.

Compaction quality inspection of soil subgrade:

1, mainly check the compactness and deflection value of each layer, and take measures to improve those that do not meet the quality standards.

2, the road bed should be smooth and solid, no obvious wheel tracks, boiling, waves, peeling and other phenomena.

3, embankment slope should be dense, stable and smooth.

Please adopt