Mat Foundation Settlement

It has been found that for the same loading intensity and soil condition the differential settlement in a mat foundation is about 1 2 than that of a spread foundation.

Mat foundation settlement.

Mat foundation is also used for low bearing capacity soil in order to spread the load of a building and hence construct a stable foundation. Mat foundations are popular in areas where basements are common. This spreadsheet can be used to complete the design of mat foundations. It is used to reduce differential settlement of buildings.

Use of a larger foundation to produce lower soil contact pressures. Mat foundations are commonly used where settlements may be a problem for example where a site contains erratic deposits or lenses of compressible materials suspended boulders etc. Common types of mat foundation. The settlement of the mat foundation will be within limits that the structure can safely tolerate as a flexible structure.

Whereas for footings only 25 mm is specified for the same allowable differential settlement of 18 mm 3 4 inches for both cases. The settlement tends to be controlled via the following. Mat foundation is specified to bridge over pockets of weak spots in moderately weak soil. It is common to use mat foundation or deep basements to transfer the column loads to the underlying soil as well as provide floor slab for the basement.

It is a continuous thick concrete slab on the soil that extends the entire footprint of the building and increases the soil bearing capacity power. Compared to spread footings the differential settlement in a mat foundation is much more reduced as the mat bridges over the loose pockets and lenses of a soil deposit. This foundation supports the entire building loads and safely transfer it to the ground. The columns can be subjected to axial horizontal and moment forces.

If settlements beneath the mat foundation are more than the rigidity of the structure will permit a redistribution of loads takes place that will. Raft or mat foundation is used when the soil layer is unstable. Mat foundations are sometimes preferred for soils that have low load bearing capacities but that will have to support high column or wall loads. Mat foundation is also known as the raft foundation.

Under some conditions spread footings would have to cover more than half the building area and mat foundations might be more economical. Thus an allowable maximum settlement of 50 mm is usually specified for raft foundations.