The primary purpose of a retaining wall is to support a soil mass and prevent it from collapsing, thereby protecting structures or infrastructure located behind the wall.

Gravity walls are typically used for heights up to 6 meters due to their stability and simplicity of construction. They rely on their own weight to resist overturning and sliding forces.

The stem is the main structural element of a cantilever retaining wall. It is a vertical or nearly vertical wall that extends above the ground level and retains the soil mass.

The heel of a gravity retaining wall is the portion of the wall that extends beyond the toe and provides stability against overturning. It helps to resist the moment caused by the soil pressure acting on the wall.

Sheet pile walls are suitable for soft or loose soil conditions because they can be driven into the ground without the need for extensive excavation. They are commonly used in waterfront structures and excavations.

Weep holes are small openings provided in a retaining wall to allow water to drain from behind the wall. This helps to prevent the buildup of hydrostatic pressure, which can lead to the failure of the wall.

Mechanically stabilized earth (MSE) walls are commonly used for highway embankments due to their flexibility, ease of construction, and ability to accommodate settlement. They consist of layers of soil reinforced with geosynthetic materials.

The stability of a retaining wall is primarily determined by the soil type and properties, including its shear strength, density, and compressibility. These factors influence the lateral earth pressure acting on the wall and the wall's ability to resist overturning and sliding.

The backfill in a retaining wall system is placed behind the wall to increase its stability. It provides additional weight to resist overturning and sliding forces and helps to distribute the lateral earth pressure more evenly.

Buttressed walls are suitable for retaining tall soil masses and heavy surcharge loads due to their increased stability. They consist of a series of vertical buttresses connected by a thin wall, which helps to distribute the lateral earth pressure more effectively.

The toe of a gravity retaining wall is the portion of the wall that extends in front of the heel and helps to prevent sliding of the wall. It provides additional resistance to the lateral earth pressure and helps to anchor the wall to the foundation.

Spread footings are the most common type of foundation used for retaining walls. They are typically used for walls of moderate height and in stable soil conditions. Spread footings distribute the load of the wall evenly over a large area of soil.

Cantilever walls are suitable for retaining soil masses in areas with limited space. They consist of a vertical or nearly vertical wall that is supported by a foundation at its base. Cantilever walls are relatively thin and can be constructed in confined spaces.

A surcharge load is an additional load placed on top of the soil mass retained by a retaining wall. It is used to increase the stability of the wall by increasing the overturning resistance. Surcharge loads can be permanent or temporary.

Sheet pile walls are commonly used for temporary applications due to their ease of installation and removal. They consist of interlocking steel or concrete sheets that are driven into the ground. Sheet pile walls can be used to retain soil masses and provide temporary support during construction or excavation.