The uneven settlement of the upper soil mass and the soil mass on both sides of the rigid structure buried under the embankment will often produce excessive additional pressure on the top of the structure. The vertical earth pressure coefficient can reach 1.2, or even 2.0 when the fill is high, that is, there is stress concentration on the top of the structure, resulting in cracking and destruction of the underground structure.

EPS, as an ultra light subgrade filler, is widely used abroad. The practice has proved that EPS has good thermal insulation, light self weight, strong self-supporting and other excellent properties, and has good treatment effect on solving problems such as subgrade frost damage, bridge head bump, subgrade instability, new and old subgrade splicing, etc.