Undrained cyclic shear response evaluation of sand based on undrained monotonic ring shear tests

The equation of motion of an undrained torque-controlled ring shear apparatus is formulated in a Newmark sliding block manner to evaluate the undrained cyclic shear response of a saturated clean sand with initial (static) shear stress. The computational procedure employs the shear resistance–displacement curve from undrained monotonic shearing as an estimate of the undrained yield strength under cyclic loading conditions. The numerically assessed cyclic response of sand in the ring shear apparatus is compared with the experimental data from undrained cyclic ring shear tests. The results of this study enhance the accuracy of a sliding block method for the assessment of seismically induced undrained displacements on shear surfaces in a saturated cohesionless soil using the experimental data from undrained monotonic shearing.