Reserch on the prediction of settlement of a large-scale reclaimed island

在大型填海造岛建设中，预测下伏构造更新世粘土的屈服后压缩是十分重要的。本研究的目的是建立一种预测更新世粘土屈服后行为的方法。本文首先建立了考虑塑性屈服对粘土结构劣化影响的更新世粘土屈服后压缩模型。采用弹粘塑性有限元法将压缩模型纳入数值计算过程。采用屈服后压缩模型的弹粘塑性有限元分析方法，对海上机场建设填海粘土地基的应力和变形进行了分析。计算结果表明，在更新世粘土沉积中，即使在更新世粘土中的透水砂层中，沉降也没有明显的超孔隙水压力消散。第二部分研究了海相黏土的压缩特性，作为评价更新世黏土压缩特性的一项重要工作。通过Fallcone试验、Vane剪切试验和固结试验的结果表明，粘土的力学特性具有一定的液限值和空隙比。利用这些特定的液限和空隙比值，提出了重构海相粘土归一化压缩曲线的广义e-logp方程。

In the construction of a large-scale reclaimed island, it is very important to predict the post yield compression of underlying structural Pleistocene clay. The aim of this reserch is to establish a method of predicting the post yield behavior of Pleistocene clay.In the first part of this research, post yield compression modelling for Pleistocene clay is proposed, considering the effect of deterioration of clay structure due to plastic yielding. The compression model is incorporated into the numerical procedure in terms of elasto-viscoplastic finite element method. Stress and deformation of the reclaimed marine clay foundation due to offshore airport construction is assessed by the elasto-viscoplastic finite element analysis with post yield compression model. Based on the calculated performance, it is found that settlement advaces without a significant dissipation of excess pore water pressure in the Pleistocene clay deposits, even in the permeable sand layrs among Pleistocene clays.In the second part of this reserch, the compression characteristics of reconstituted marine clays are examind as a flame work for the assessment of compression characteristics of Pleistocene clay. Based on the results of a number of Fallcone tests, Vane shear tests and consolidation tests, it is shown that the mechanical properties of clays are characterized by a specific values of the liquid limit and void ratio. Using these specific values of liquid limit and void ratio, the generalized e-logp equation termed normalized compression curve of reconstituted marine clays is proposed.