Retaining walls are used to hold earth or any other material. It prevents soil from taking its natural position and makes the area above and below it usable.
The wall has 3 parts. Stem, Toe Slab, and Heel Slab. The toe and Heel slab make up for the foundation of the wall. Some walls have a key provided in the footing to prevent it from sliding.
The stem may be provided with drain holes with a slope for the water drainage. A similar sloping perforated pipe may be provided below the same for water drainage. The soil behind the stem can be coarse aggregates so that water percolates and exits via drains.
The portion of the wall in contact with the soil is usually provided with some kind of waterproofing. This waterproofing can be in the form of EPDM membrane or waterproofing boards.