中文摘要：

以上海复兴东路越江隧道江底旁通道冻结施工中的第⑥层原状和冻融作用后的暗绿色粉质粘土为研究对象，利用扫描电镜对两种土的微结构基本单元的形状和大小、基本单元体的接触状态、基本单元体间的联结形式、孔隙形状和大小等方面进行研究．在此基础上，将原状土和冻融土的静三轴试验与动三轴试验的结果分别作了对比．试验结果显示，该土体经冻融作用后，胶结体以及土颗粒发生了明显的破坏，孔隙变大，导致了土体内粘聚力与最大动应力的显著下降，隧道运营时，应严格控制冻结区域的车速．

英文摘要：

The microscopic behavior of dark green silty soil of the 6th storey is studied by means of scanning electronic microscope. The shape, size and contact condition of the basic elements of the soil microscopic structure, and the shape and the size of the pore are further studied. In addition, a comparative study is made to analyze the experiment result of Cu and dynamic test. The mechanic characteristics of common soil and those of melted soil are revealed and their influences on dark silty soil after being frozen are theoretically illustrated from microscopic perspective.