The stress‐dependent shear strength behaviour of rockfill is frequently estimated by simple shear strength parameter. A linear shear relation between vertical and shear stresses is almost always applied. However, the actual shear strength behaviour of rockfill differs from this theoretical line. A curve is formed which indicates that strong shear strength at low stresses gradually decreases with increasing stress.
The shear strength behaviour is influenced by many aspects, such as grain size distribution, compressive strength of the original rock, saturation, stress conditions, grain shape, etc. Reliable large‐scale shear tests are not usually available and a realistic non‐linear shear strength function has to be estimated using analytical approaches. Only rarely are case studies available for rockfill dams under dynamic loads induced by earthquakes. However, it is assumed that typical rockfill materials will resist dynamic loads.