General shear failure occurs in narrow, shallow footings on dense, incompressible soils. Local shear failure features slip lines below and slightly into footings on weaker soils or wider/deeper footings. Punching shear failure results from highly compressible soils, compressing under footings without defined slip lines or lateral soil involvement.

2. OVERVIEW
• General shear failure
• Local shear failure
• Punching shear failure

3. GENERAL SHEAR FAILURE
• It is a characteristic of narrow footing of shallow depths
• Resting on strong dense soil that are relatively
incompressible.

4. LOCAL SHEAR FAILURE
• For weaker, more compressible soil and wider or deeper
footings, the failure may be taken as local shear failure
of punching shear failure.
• Local shear failure is characterized by well defined slip
lines below the footing but extending only a short
distance into the oil mass.

5. PUNCHING SHEAR FAILURE
• In highly compressible soils the punching shear mode of
failure results.
• This is characterized by lack well defined slip lines
below the footing. The vertical movement of footing is
primarily due to compression of soil below the footing
with the soil on the side not being involved.