A 'plate loading test'*Ĭan give misleading results if the proposed footing width is much lager The depth at which the soil pressure need to be consideredĭepends on the size of the proposed footings. As can be seenįrom Figure 2 it is important to investigate the site to a greater depthįor large footings. Internet link "Diminishing soil pressure"Īn indication of the depth of soil affected by a footing. The pressure should be followed up to a depth of 2B The width of a footingĭetermines at what depth the pressure from the building is reduced toĪ neglected value. Some idea of the depth of soil affected by a footing. As can be seen the pressure from the building loadĭecreases (see lower diagram in Figure 1) while the pressure from the The circles, knownĪs bulbs of equal pressure, give an indication of the vertical pressureīelow the foundation. On the soil mass will induce stresses within the soil. The pressure at depth h in a foundation is due to the weight of the buildingĪnd the self-weight of the soil above the depth h.įigure 1 illustrates the theory of pressure distribution within the foundation. Site conditions and the ability of the building system to accommodate Under service loads over the design range of soil moisture conditions.Īllowable bearing pressure shall be taken into consideration both the That can be sustained by the foundation from the proposed footing system (Residential slabs and footings-Construction) the maximum bearing pressure The allowable bearing pressure is according AS2870-1996 Is the ultimate bearing capacity divided by an appropriate factor of safety. This is based entirely on the strength of the soil and Of contact pressure to which the soil can be subjeted without risk of The maximum safe bearing capacity is the maximum value The ultimate bearing capacity for a typical foundationīase is the average vertical pressure on the ground that leads to failureīy shear, in other words the average contact pressure between the foundationĪnd the soil that will produce shear failure in the soil The requirements for the classification of a site and the design and construction of a footing system for a single dwelling house, townhouse or the like are found in AS 2870-1996 Residential slabs and footings-Construction. For large building constructions a geotechnical site investigation according to AS 1726-1993 should be carried out. The term foundation may refer in some sources to footings.) The structural load of a building must be safety and economically transferred to the ground without unacceptable settlement.Ī site investigation should be carried out to find out what type of structure it supports, its loading and the amount of movement that can be tolerated. (Note that we make a distinction between footings and foundation. The bearing capacity depends on the behaviour of the ground under a building and its interaction with the foundation. Bearing capacity, plastic falure, slip circle & retaining structures Bearing capacity, plastic falure, slip circle & retaining structures Bearing capacity of soil
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