Earth Retaining Structures
Expert-defined terms from the Postgraduate Certificate in Geotechnical Engineering & Soil Mechanics course at London School of Planning and Management. Free to read, free to share, paired with a globally recognised certification pathway.
Anchored Bulkhead #
An anchored bulkhead is a type of retaining wall that uses cables or anchors to transfer the earth pressure to a stable foundation or soil layer behind the wall. This wall is commonly used in waterfront structures, where the soil is soft and weak.
Battered Wall #
A battered wall is a type of retaining wall that leans back towards the soil it is holding back, creating a backward slope or batter. This design helps to increase the stability of the wall and reduces the risk of sliding or overturning.
Cantilever Wall #
A cantilever wall is a type of retaining wall that is supported by a single stem or column, extending from the base foundation. This wall is often used in areas with limited space, and the design allows for minimal excavation and disturbance to the surrounding soil.
Drainage #
Drainage refers to the removal of water from the soil behind a retaining wall. Proper drainage is essential to ensure the stability of the wall, as water can exert significant pressure on the wall and cause it to fail.
Earth Pressure #
Earth pressure refers to the force exerted by the soil on a retaining wall. The amount of earth pressure depends on the weight of the soil, the angle of internal friction, and the water content of the soil.
Geotextile #
A geotextile is a permeable fabric used in soil stabilization and reinforcement. Geotextiles can be used to improve drainage, reduce erosion, and increase the stability of retaining walls.
Gravity Wall #
A gravity wall is a type of retaining wall that relies on its weight to resist the earth pressure. These walls are often made of concrete, masonry, or stone, and are commonly used in areas with stable and strong soil.
Groundwater #
Groundwater refers to the water that exists in the pores of the soil or rock below the ground surface. Groundwater can exert significant pressure on a retaining wall, and proper drainage is essential to ensure the stability of the wall.
MSE Wall #
MSE (Mechanically Stabilized Earth) Wall is a type of retaining wall that uses soil reinforcement to stabilize the soil and resist earth pressure. MSE walls are often made of precast concrete panels or geotextile materials.
Passive Earth Pressure #
Passive earth pressure refers to the force exerted by the soil when the retaining wall moves away from the soil. This pressure is generally lower than the active earth pressure.
Pile Foundation #
A pile foundation is a type of deep foundation that uses long, slender columns or piles to transfer the weight of the structure to a stable soil layer or rock below the ground surface. Pile foundations are commonly used in areas with weak or unstable soil.
Retaining Wall #
A retaining wall is a structure used to hold back soil or water, preventing erosion, landslides, or flooding. Retaining walls can be made of various materials, including concrete, masonry, stone, or steel.
Surcharge Load #
A surcharge load refers to the additional weight placed on a retaining wall, such as a building, road, or vehicles. Surcharge loads can increase the earth pressure and require additional design considerations.
Tieback Anchor #
A tieback anchor is a type of anchor used to reinforce a retaining wall. The anchor is installed in the soil behind the wall and connected to the wall with a cable or rod. Tieback anchors help to transfer the earth pressure to a stable foundation and increase the stability of the wall.
Toe #
The toe refers to the bottom portion of a retaining wall, where it meets the soil. Proper design of the toe is essential to ensure the stability of the wall and prevent sliding or overturning.
Water Table #
The water table is the level below which the soil is saturated with water. The water table can exert significant pressure on a retaining wall, and proper drainage is essential to ensure the stability of the wall.
Active Earth Pressure #
Active earth pressure refers to the force exerted by the soil when the retaining wall moves towards the soil. This pressure is generally higher than the passive earth pressure.
Anchor #
An anchor is a device used to reinforce a retaining wall by transferring the earth pressure to a stable foundation or soil layer behind the wall. Anchors can be made of various materials, including steel, concrete, or composites.
Backfill #
Backfill refers to the soil or material placed behind a retaining wall. Proper backfill material and compaction are essential to ensure the stability of the wall.
Base #
The base refers to the bottom portion of a retaining wall, where it meets the foundation. Proper design of the base is essential to ensure the stability of the wall and prevent sliding or overturning.
Buttress #
A buttress is a structural element used to reinforce a retaining wall by providing additional support. Buttresses can be located at various points along the wall, depending on the design requirements.
Deadman #
A deadman is a type of anchor used to reinforce a retaining wall. The anchor is a large block or concrete slab buried in the soil behind the wall and connected to the wall with a cable or rod. Deadmen help to transfer the earth pressure to a stable foundation and increase the stability of the wall.
Diaphragm Wall #
A diaphragm wall is a type of retaining wall that uses a reinforced concrete panel to resist the earth pressure. Diaphragm walls are often used in deep excavations, such as underground parking garages or basements.
Factor of Safety #
The factor of safety is a design consideration used to ensure the stability of a retaining wall. The factor of safety is the ratio of the wall's resistance to the earth pressure to the actual earth pressure. A factor of safety of 1.5 or higher is generally recommended.
Flexible Wall #
A flexible wall is a type of retaining wall that can move or deform under the earth pressure. Flexible walls are often made of geotextile materials or segmental concrete blocks.
Geogrid #
A geogrid is a type of soil reinforcement material used to increase the stability of retaining walls. Geogrids are often made of high-density polyethylene (HDPE) or polypropylene (PP) and have a grid-like structure.
Helical Pile #
A helical pile is a type of deep foundation element used to transfer the weight of a structure to a stable soil layer or rock below the ground surface. Helical piles are often used in areas with weak or unstable soil.
Key #
A key is a structural element used to reinforce a retaining wall by providing additional support. Keys can be located at various points along the wall, depending on the design requirements.
Lateral Pressure #
Lateral pressure refers to the force exerted by the soil on a retaining wall in a horizontal direction. Proper design of the wall is essential to resist the lateral pressure and ensure the stability of the wall.
Nailing #
Nailing is a technique used to reinforce a retaining wall by installing metal or synthetic rods into the soil behind the wall. The rods are anchored to the wall to transfer the earth pressure to a stable foundation.
Passive Stress #
Passive stress refers to the force exerted by the soil when the retaining wall moves away from the soil. This stress is generally lower than the active stress.
Reinforced Earth #
Reinforced earth is a type of retaining wall that uses soil reinforcement to stabilize the soil and resist earth pressure. Reinforced earth walls are often made of precast concrete panels or geotextile materials.
Rigid Wall #
A rigid wall is a type of retaining wall that resists the earth pressure by its weight and stiffness. Rigid walls are often made of concrete or masonry.
Slope Stability #
Slope stability refers to the resistance of a slope to sliding or failure. Proper design of the slope and retaining wall is essential to ensure slope stability and prevent landslides or erosion.
Soil Nail #
A soil nail is a type of anchor used to reinforce a retaining wall. The anchor is a steel rod installed in the soil behind the