A circular foundation of diameter 8m supports a tank. The base of the foundation is at 1m below the ground surface. The vertical load is 20 Mn. The tank foundation is supported by a soil with undrained shear strength equal to 80 kPa and saturated unit weight of 19 KN/M3, dry unit weight of 17.6 kn/m3
and angle of internal friction equal to 25 degrees. Ground water table is at 4 meters below the surface and assumed to be stable. Fourteen months after the tank was constructed during a week of intense rainfall, the foundation failed. It was speculated that failure occurred by bearing capacity failure. Clarify whether this is so or not.