ABSTRACT
The contact constitutive relation as proposed by Cundall & Strack (1979) has been used. The spring constants in normal and tangential directions are denoted by kn and kt , respectively. Friction is incorporated at the contact level by the condition |f ct | ≤µf cn , where f cn and f
c t are the normal and tangential com-
ponents of the force at contact c. Furthermore, the no-tension condition applies, according to which only compressive normal forces are allowed, since for tensile normal forces the contact is considered to be disrupted for cohesionless materials.
