Applicability of a two-parameter failure criterion to wheat en masse

A two-parameter failure criterion established for cohesionless soils was applied to wheat en masse. Two parameters, failure constant η and exponent m, were determined for wheat at a moisture content of 8.1% (d.b.) and initial bulk density of 817 kg/m³. The criterion satisfactorily describes the failure of wheat en masse in the triaxial compression stress state. When both parameters are nonzero, the lateral to vertical stress ratio (k-value) determined from the two-parameter criterion increases with the vertical stress, whereas when the failure exponent m is zero, the ratio is constant and approximately equal to that determined from the Mohr-Coulomb failure criterion.