In architecture and structural engineering, haunches refer to the thickened or reinforced portions of a structural element, such as a beam or a pipe, typically located at points of high stress or support.
When applied to pipes, haunches are commonly used at the base of buried pipelines, particularly where the pipe meets the bedding material.
These haunches provide additional support and stability, helping to distribute loads more evenly and prevent deformation under earth pressure or external loads.
Proper haunching is crucial in underground piping systems to maintain alignment, prevent settlement, and ensure long-term structural integrity.
The quality of the haunch material and its compaction around the lower sides of the pipe are essential factors in the overall performance of the piping system.
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Haunches detail drawing – 1
In construction, haunches for pipe detail drawings refer to the illustrated section of a pipe installation—especially for buried pipes—that shows how material (typically granular or compacted soil) is placed and compacted around the lower sides of the pipe. This area, known as the pipe haunch zone, lies between the bottom of the pipe (springline) and the bedding layer.
Key Points in a Pipe Haunch Detail Drawing:
Pipe Bedding:
The material layer beneath the pipe, typically well-compacted sand or gravel, which provides foundational support.
Haunch Area:
The zone from the bedding up to the springline of the pipe. The haunch material must be properly compacted to prevent pipe movement and deformation due to soil loads.
Embedment Material:
Drawings usually specify the type and gradation of material to be used (e.g., granular fill, crushed stone), including compaction requirements (e.g., 90–95% Proctor density).
Backfill Zones:
Above the springline, backfill is placed and compacted in layers to ensure the pipe is fully supported and protected.
Pipe Dimensions:
The drawing will show pipe diameter, trench width, depth of embedment, and sometimes slope or alignment if relevant.
Notes and Specifications:
Important construction notes may include required ASTM standards, minimum compaction levels, material types, and handling instructions.
Purpose of Haunching in Drawings:
- Ensures correct installation technique is followed.
- Prevents pipe deformation or collapse under load.
- Enhances load transfer from the pipe to surrounding soil.
- Minimizes risk of pipe misalignment or joint failure.
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