The plastic geogrid has a network structure. When it is backfilled, the pore water pressure can dissipate faster and the average settlement can also be achieved in the settlement process. Therefore, the use of plastic geogrid can more effectively guarantee the safety of embankment backfill, so as to speed up the settlement of this kind of embankment. This is of great significance to the reinforcement of cohesive soil subgrade.

Under the condition of high pressure and low porosity, with the effect of natural gravity, the physical effect of soil volume will change. Among them, there will be crimping, sliding, rolling and crushing of soil particles, and the sliding, rolling and sliding of soil particles, rolling and friction of soil particles are closely related. For the foundation backfill, the compaction settlement will be permanent and hard to recover. This phenomenon exists in two stages: one is the sinking phenomenon in the engineering stage, which requires filling to the design elevation. The second is the sinking phenomenon after the project, which will have a greater impact on the later operation. Therefore, it is necessary to reduce the settlement difference, and the key factor is to reduce the lateral displacement of embankment fill.

Plastic geogrid can improve the bearing capacity of subgrade and increase the stability of subgrade, and also can adjust the uneven settlement, which can reduce the settlement difference of subgrade rapidly. Because the glass fiber plastic geogrid and sand gravel layer together constitute the achievement phenomenon of the composite cushion with much greater rigidity than the soft soil, and play a new role in the distribution of the Ya load imposed on the upper part. Under the effect of its infiltration and water removal, it can make the subgrade stress tend to be balanced, it can accelerate the water removal and consolidation of the soft foundation, and promote the achievement of the average settlement of the embankment.