Understanding the Flank Wall in Civil Structures

The question asks to identify the specific name for a retained wall that serves as a continuation of the abutments in a structure, extending both upstream and downstream.

Let's examine the options provided:

• Border wall

  A border wall is a general term and doesn't specifically describe a retained wall continuing from an abutment in civil engineering structures like bridges or culverts.

• Flank wall

  A flank wall is a type of retained wall that is built in continuation of the abutments of a bridge or other similar structure. Its primary functions include retaining the earth fill behind the abutment and guiding the flow of water (in the case of a bridge over a waterway) upstream and downstream, preventing scour and erosion around the abutment.

• Base wall

  A base wall typically refers to a wall forming the base or foundation of a structure, or sometimes the lower part of a wall. It does not fit the description of a wall continuing from an abutment.

• Parapet wall

  A parapet wall is a low protective wall along the edge of a bridge, balcony, or roof. Its main purpose is safety (preventing falls) rather than retaining earth or being a direct structural continuation of the main load-bearing abutment in the sense described.

Based on the definitions, the term that correctly describes a retained wall in continuation of abutments, both upstream and downstream, is a flank wall.

Detailed Explanation of Flank Wall Function

Flank walls play a crucial role in the stability and longevity of structures supported by abutments, particularly bridges. They ensure that the soil embankment behind the abutment is properly retained, preventing it from eroding or collapsing. Furthermore, by extending upstream and downstream, they help streamline the flow of water under the bridge, reducing turbulence and protecting the abutment foundations from potential damage caused by water currents and scour.

Revision Table: Key Civil Engineering Walls

Additional Information on Bridge Abutments and Walls

Abutments are essential components of bridges and similar structures, providing support for the superstructure and retaining the earth fill that forms the approach embankment. Various types of walls are associated with abutments, each serving a specific purpose:

• Wing Walls: These are also retained walls extending from the abutment, often at an angle. While similar to flank walls in function (retaining earth, guiding flow), they are typically distinct components or specific types of flank walls depending on the design and angle relative to the main abutment face. Flank walls often refer to walls parallel or in line with the abutment face extending along the embankment edge.
• Return Walls: A type of wing wall that runs parallel to the roadway or embankment edge, effectively "returning" towards the embankment.
• Splayed Wing Walls: Wing walls that angle outwards from the abutment, used to guide water flow more gradually.

The term "flank wall" as described in the question fits the role of a retained wall extending directly from the abutment along the length of the embankment's edge, both upstream and downstream.