抄録
A new stress plane in the three-dimensional stress space has been proposed on an idea that soil is one of the materials governed by the frictional law, i.e., the shear-normal stress ratio. The new stress plane is named "Spatial Mobilized Plane (SMP)". It has been verified by data of various kinds of shear tests including true triaxial tests that stress-strain behaviors of soil under three principal stresses can be uniquely expressed on the SMP. Furthermore, a new yield condition of soil J1·J2/J3=const. (J1, J2, J3 : the first, second and third effective stress invariants) has been also proposed on condition that soil yields when the shear-normal stress ratio on the SMP reaches a certain value. This proposed yield condition is in an interesting correspondence with the Tresca, von Mises and Mohr-Coulomb criteria.
