Short Answer:

Gravity retaining walls are solid structures that hold back soil mainly by using their own weight. They are typically made from concrete, stone, or brick masonry and rely on mass and stability to resist the lateral pressure of the soil behind them. No reinforcement is needed in basic gravity walls.

These walls are used where the height is moderate, and strong support is needed without complex construction. They are commonly used in road embankments, garden terraces, hilly terrain, basement walls, and landscape retaining structures due to their simplicity and effectiveness.

Detailed Explanation

Gravity Retaining Walls and Their Usage

A gravity retaining wall is one of the oldest and simplest types of retaining structures used in civil engineering. It works entirely based on self-weight to resist the horizontal pressure exerted by the retained soil. Unlike reinforced concrete walls that depend on steel reinforcement to resist tension, gravity walls resist both sliding and overturning purely through their mass and base width.

Gravity walls are usually made of heavy materials such as plain concrete, stone masonry, or brick masonry. These materials provide the necessary mass to withstand the lateral earth pressure. Because of their straightforward construction and ability to perform without steel, they are commonly used in various low to medium-height applications.

What Are Gravity Retaining Walls

1. Principle of Resistance

• Gravity walls resist lateral soil pressure through their own weight.
• They do not require reinforcement for stability.
• The thickness and base width are proportioned to provide resistance against sliding, overturning, and bearing failure.
• The pressure from the retained soil acts horizontally, while the wall’s weight acts vertically to balance the force.

2. Shape and Construction

• Common shapes include triangular, trapezoidal, or stepped sections, depending on height and design.
• The base is made wide to lower the center of gravity and increase stability.
• Sometimes, the front face is made vertical, and the back face is sloped to reduce material usage.

3. Materials Used

• Plain cement concrete (PCC) is widely used for short walls.
• Stone or rubble masonry is preferred in rural and hilly areas.
• Brick masonry is also used in lightweight applications.
• In some cases, precast concrete blocks or dry stone gravity walls are also used.

Where Gravity Retaining Walls Are Used

1. Road Embankments and Highways

• Used along cuttings or slopes where the soil needs to be retained safely beside the road.
• Helps prevent landslides or soil erosion along the road edge.

2. Basement and Foundation Support

• Gravity walls are used in basement construction to retain the surrounding soil when the basement is excavated.

3. Landscape and Garden Retaining Walls

• Used in gardens and parks to create terraces and level differences.
• Aesthetic appeal is also achieved by using stone or brick masonry.

4. Hilly and Sloped Areas

• In mountain regions, gravity walls support stepped terrain or roadways.
• Common in retaining earth behind structures built on slopes.

5. Culverts and Minor Bridge Abutments

• Gravity walls are used to retain soil near culvert openings and small bridge ends due to simplicity in design.

6. Temporary Retaining Structures

• For small projects or temporary slope protection, dry stone gravity walls can be built quickly and removed later.

Conclusion

Gravity retaining walls are massive, stable structures that resist soil pressure using their own weight without reinforcement. They are best suited for small to medium-height applications such as road embankments, gardens, and hilly terrains. With proper design and construction, gravity walls offer a simple, cost-effective, and reliable solution for soil retention needs.