Investigation of the Physical, Chemical and Mechanical Properties of Ariake Clay under the Reclamation Dick and Analysis of the Behavior of the Reclamation Dike by Finite Element Method

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The physical, chemical and mechanical properties of Ariake clays under/around the reclamation dikes were examined based on core boring data and soil test results. The following main results were obtained : (1) Ariake clay layers under the reclamation dike are normally consolidated and the consolidation settlement of the alluvial Ariake clay layer is considerably larger than that of the deeper layers. (2) There is the unique relation between fall cone penetration depth and vane shear strength for undisturbed Ariake clays. Liquid limit (W_<Lf>) obtained by fall cone method is well coincident with that (W_L) obtained by JIS method in W_L≦100% and the difference between rLf and W_L increases with the increase of W_L in W_L>100%. (3) The rates of strength increase and the internal friction angles of remolded Ariake clays were 15〜20, 5〜20% greater than those of undisturbed ones respectively. The grain size distribution of Ariake clay has an effect on Hvorslev's strength parameters. Irreversibility ratio (Λ) of Ariake clay is in the range of 0.6〜0.8 and is not affected with grain size distribution and plasticity index (I_p). (4) The results of the consolidation test using constant rate of strain loading for remolded Ariake clays are independent on strain rate. To the contrary, the consolidation yield stress of undisturbed Ariake clays is dependent on strain rate.Moreover, the behavior analyses of the reclamation dike in the field and of the footing in the centrifuge model test using the elasto-plastic finite element method were carried out. It was found from the comparisons of the results of these analyses with those of the field observation and with those of the centrifuge model test that this analysis method was sufficiently applicable to the behavior analysis of the reclamation dike on the soft ground.