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Settlement is the downward movement or the sinking of a structure's foundation. It is mostly caused by changes in the underlying soil, such as drying and shrinking, wetting and softening, or compression due to the soil being poorly compacted when construction started.
Some settlement is quite normal after construction has been completed.
Unequal settlement or differential settlement is non-uniform settlement. It may cause significant problems for buildings. Distortion or disruption of parts of a building may occur due to
* unequal compression of its foundations;
* shrinkage, such as that which occurs in timber-framed buildings as the frame adjusts its moisture content; or
* undue loads being applied to the building after its initial construction.
Settlement should not be confused with ''
Settlement is the downward movement or the sinking of a structure's foundation. It is mostly caused by changes in the underlying soil, such as drying and shrinking, wetting and softening, or compression due to the soil being poorly compacted when construction started.
Some settlement is quite normal after construction has been completed.
Unequal settlement or differential settlement is non-uniform settlement. It may cause significant problems for buildings. Distortion or disruption of parts of a building may occur due to
* unequal compression of its foundations;
* shrinkage, such as that which occurs in timber-framed buildings as the frame adjusts its moisture content; or
* undue loads being applied to the building after its initial construction.
Settlement should not be confused with ''subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...
'' which results from the load-bearing ground upon which a building sits reducing in level, for instance in areas of mine workings where shafts collapse underground.
Traditional green oak-framed buildings are designed to settle with time as the oak seasons and warps, lime mortar
Lime mortar or torching is a masonry mortar (masonry), mortar composed of lime (material), lime and an construction aggregate, aggregate such as sand, mixed with water. It is one of the oldest known types of mortar, used in ancient Rome and anci ...
rather than Portland cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar (masonry), mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in th ...
is used for its elastic properties and glazing will often employ small leaded lights which can accept movement more readily than larger panes.
Measurement of settlements
The magnitude of settlements can be measured using different techniques such as: *Surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...
* Settlement cells
* Tiltmeter
A tiltmeter is a sensitive inclinometer designed to measure very small changes from the vertical level, either on the ground or in structures. Tiltmeters are used extensively for monitoring volcanoes, the response of dams to filling, the small ...
s
* Borehole extensometer
An extensometer is a device that is used to measure changes in the length of an object. It is useful for stress- strain measurements and tensile tests. Its name comes from "extension-meter". It was invented by Charles Huston who described it ...
s
* Full-profile gauge
* Settlement platforms
See also
*Soil consolidation
Soil consolidation refers to the soil mechanics, mechanical process by which soil changes volume gradually in response to a change in pressure. This happens because soil is a three-phase material. The first phase consists of soil grains, and a ...
References
{{Authority control Building defects Foundations (buildings and structures) Structural engineering