2018 Volume 13 Issue 3 Pages 205-221
A series of stress-controlled undrained cyclic loading tests using a torsional simple shear apparatus are carried out on sand specimens by applying harmonic and irregular shear stresses to evaluate cumulative dissipated energies during the liquefaction process and to examine the effect of stress irregularity on the dissipated energy versus induced strain and pore-pressure buildup. Tests with harmonic stresses show that the energy for the same soil, which is roughly proportional to effective confining stress, is almost uniquely correlated with pore-pressure buildup and induced strains during cyclic loading irrespective of the stress amplitudes and the number of loading cycles. Irregular loading tests also yield almost unique correlations between them despite widely varied stress amplitude and the number of zero-cross Nzc. In the irregular loading, however, the dissipated energy corresponding to larger post-liquefaction strain tends to fluctuate and also decrease with increasing Nzc due to wave irregularity, necessitating some allowance of variation for design.
