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

根据钻孔取心数据和土工试验结果，研究了垦堤下/围区有明黏土的物理、化学和力学性质。主要研究结果如下：(1)填海堤下有明黏土层固结正常，且冲积性有明黏土层固结沉降明显大于其深层。(2)原状有明黏土的落锥侵彻深度与叶片抗剪强度之间存在独特的关系。落锥法得到的液限（W_<Lf>）与JIS法得到的液限（W_L）在W_L≦100%时吻合良好，且在W_L>100%时，随着W_L的增大，rLf与W_L的差值增大。(3)重塑后的有明黏土强度增长率和内摩擦角分别比未扰动的高15 ~ 20%和5 ~ 20%。有明黏土的粒度分布对Hvorslev强度参数有影响。有明黏土的不可逆性比（Λ）在0.6 ~ 0.8之间，不受粒径分布和塑性指数（I_p）的影响。(4)有明黏土的恒应变加载固结试验结果与应变速率无关。相反，未受扰动的阿里克黏土固结屈服应力与应变速率有关。采用弹塑性有限元法对围垦堤防的现场性能和离心模型试验中的地基性能进行了分析。将这些分析结果与现场观测结果和离心模型试验结果进行比较，发现该分析方法足以适用于软土地基上围垦堤防的行为分析。

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.