back-filling
Technical term in civil engineering and construction for filling the space behind a retaining wall, abutment, or similar structure with material such as soil, gravel, or concrete.
Crushed stone is often used for back-filling behind retaining walls.
The selection of back-fill material is done with drainage in mind.
Compound of 裏 (ura, 'back, rear') and 込め (gome, from 込める komeru, 'to put in, fill'). The term literally means 'filling the back side'.