Design of Shallow and Deep Foundations for Earthquakes

Foundations may undergo severe distress during an earthquake. One such example of foundation failure involving toppling of apartment blocks due to liquefaction during the 1964 Niigata Earthquake is presented in Figure 1. Earthquake effects on shallow and deep foundations are accounted for by designing them structurally to provide necessary strength and ensure serviceability. Strength considerations essentially involves ensuring that the foundation loads remain well below that dictated by the allowable bearing capacity under seismic conditions and serviceability is ensured by designing the substructure for the estimated permanent ground deformation. Simple procedures for estimating bearing capacity and permanent ground deformation under earthquake conditions are presented in this note.