A crib wall is a type of retaining structure created by stacking pre-engineered members to form a series of interconnected, open cells or "cribs" that are then filled with material such as soil or rock.
Crib walls are distinguished as one of the oldest gravity wall systems. This fundamental characteristic means they rely on the sheer mass of the structure itself – including the weight of the stacked members and the material filling the cells – to resist the lateral earth pressure from behind.
How Crib Walls Function
The system is comprised of a series of stacked members creating hollow cells filled with soil or rock. These members are typically arranged in layers, interlocked at the face and extending back into the soil mass. This interlocking framework, combined with the weight of the granular fill within the cells, forms a heavy, stable block capable of retaining soil or supporting vertical loads.
Materials and History
Historically, crib walls were often constructed using durable timber, particularly in areas with readily available logs. A notable example referenced is the telephone pole crib wall built during the Second World War by the California Division of Highways near Sonoma, California. Today, while timber is still used, precast concrete members are also widely utilized for their longevity and strength.
Applications of Crib Walls
Due to their structural integrity and ability to handle drainage, crib walls are commonly employed in various applications, including:
- Retaining Steep Slopes: Stabilizing embankments along highways, railways, or in challenging terrain.
- Bridge Abutments: Providing support for the ends of bridges.
- Landscape Terracing: Creating level areas on sloped ground for gardens or usable space.
- Erosion Control: Preventing soil loss in vulnerable areas.
Key Characteristics
- Gravity System: Stability derived from self-weight and infill.
- Permeable: The open nature of the structure allows for natural drainage, reducing hydrostatic pressure buildup.
- Flexible: Can tolerate slight ground settlement better than rigid wall types.
Explore where crib walls are used
In essence, a crib wall is a robust, permeable gravity retaining structure built from stacked, interlocking members filled with granular material, a technique with a long history in civil engineering.
