Building Foundation Systems l Shallow vs Deep Foundation

This video talks about Foundation Systems. The foundation is the lower part of the building. It is constructed partially or wholly underground and it is crucial for keeping the building up, it supports and anchors the portion above and conducts its weight into the earth. It is related to the form and layout of the building above and also all the variables under the surface of the ground such as soil conditions, rock, and water below. There is a wide variety of foundation systems and they can be classified in two broad categories: 1. shallow foundations 2. deep foundations Shallow foundations are used where stable soils and soils with the compactness necessary are present near the ground surface. Deep foundations are used where the soil underneath the surface is unstable and doesn’t have a necessary capacity, compactness to hold the weight of the building. In these cases the foundation needs to go deeper passing the layer of unsuitable soil until reaching a layer of good soil support, made of either rock or dense sands and gravels to support the necessary weight. Some examples of foundations systems are: -Strip footing under foundation walls or, -Isolated footing under columns. If soil is not as stable, then the choices could be, -A mat or raft foundation, which consist of a concrete slab heavily reinforced and thick or, -A floating foundation, which is a mat foundation but placed deeper under the ground surface. The intention is excavate to the point where the weight of the excavated soil equals or is greater that the weight of the building being supported. And that’s the depth where the Mat foundation is placed. Now, for the most basic deep foundations we have: -Pile foundation -Caisson foundation Pile foundations might be of wood if treated but for larger buildings, steel, concrete-filled pipes, or precast concrete are more suitable. Caisson foundations are cast-in place concrete, the process consist of excavating a shaft in the earth and once this excavation reaches suitable soil, the shaft is filled with concrete.