Bearing failure

This is about types of shear failure in soil, describe all the three types of the bearing capacity failure of soil.
This is prepared by (Abdullah Kawkas Galaly) a student in civil engineering department at Salahaddin University in Erbil-Kurdistan region.

1. Bearing Failure Prepared by: Abdullah Kawkas Ahmed

2. Foundation Design A foundation is required for distributing the loads of the superstructure on a large area The foundation should be designated such that, the soil below: dose not fail in shear. Settlement is within safe limits.

3. Types of Shear Failures Shear failure of soil under a foundation base classified into three categories depending on the type of soil and location of foundation: General shear failure. Location shear failure. Punching shear failure.

4. General Shear Failure This type of failure happens provided that dense sand or stiff cohesive soil support the footing. Under this type, the footing moves downward slightly. A sudden failure occurs with a significant bulging of the ground surface alongside the footing . Sudden collapse happens, together with tilting of the footing. The load-settlement diagram is equivalent to stress-strain for solid sand or over-consolidated clay. The ultimate load is apparent on this curve .

5. Local Shear Failure It occurs in moderately compressible soils or loose sand. In this mode a large deformation takes place under the footing. large vertical settlement occurs prior to slight bulging of the ground surface. Tilting of footing is not necessary. D efined as the first major nonlinearity in the load-settlement curve (open circle ). Ultimate load is not clear.

6. Punching Shear Failure Occurs in very loose sands and weak clays. The loaded base sinks into soil like a punch. No bulging of ground surface and no tilting of footing occurs. Large vertical strains are involved with practically no literal deformation. After the first yield the load-settlement curve will steepen slightly, but remain fairly flat. Ultimate load is not clear .