Cyclic Shear Strength of the Nishioki Reclaimed Deposit

The stability of the saturated reclaimed deposit in the Nishioki district during cyclic shear is examined using simplified methods of liquefaction analysis. The deposit with thickness of about 3m consists of very soft silty sand, which has N-value below 3,and water content above liquid limit of 38.9%. Also, in order to obtain cyclic shear strength of the silty sand, cyclic shear tests were carried out using cyclic triaxial test apparatus. It is shown from the analyses that when the deposit is subjected to an earthquake of M=6,the deposit causes failure like the liquefaction of sand. Furthermore, it is found that though the density of the silty sand increases due to the drainage after the first cyclic shear failure, the silty sand easily fails again as compared with the first failure.