2017 Volume 73 Issue 2 Pages I_270-I_275
The liquefaction resistance of sand under sequenced earthquake motions was investigated by a series of stress-controlled, undrained hollow cylinder cyclic torsional shear tests. The ordinary sinusoidal cyclic shear stress was first applied to the specimen to a certain extent simulating the pore pressure generation in the first shock. Under such conditions with various degrees of excess pore pressure, the liquefaction resistance was evaluated against 3 different aftershocks. When the equivalent CSR* is estimated based on the effective number of waves, the test results are clearly categorized into the 2 groups with and without liquefaction. The effective number of waves well characterize the irregular loadings in the cases with residual excess pore pressure. The presented simple approach allows one to predict the risk of liquefaction during aftershocks.
