Analyses of the Constant Shear Strain Point and Velocity Distribution in the Shear Band for Geomaterials

For linear strain-softening geomaterials at post-peak,the total shear strain in the shear band(localized shear zone) is composed of the elastic strain(described by the classical elastic theory) and the local plastic shear strain due to the microstructural effect(described by the nonlocal theory or gradient-dependent plasticity).If the shear softening modulus(the absolute value of the slope of the shear stress-plastic shear strain curve) is less than two times of the shear elastic modulus,then two constant shear strain points exist in any section of a shear band.At the two points,the total shear strain is independent of the shear stress;the decrease of the elastic shear strain and the increase of the local plastic shear strain reach an equilibrium state;and the total shear velocity reaches its maximum or minimum value.With a decrease of the shear stress rate,the total shear velocity increases between the two constant shear strain points.In the shear band,the velocity distribution is nonlinear,as it is different from the traditional assumption of linear velocity distribution(neglecting the microstructural effect).