中文摘要：

基于地铁联络通道冻结法施工,以冻结温度和冻融周期为控制变量,对冻融土加载前、后微观结构进行电镜扫描试验.定性描述了冻融土经历动三轴加载后微观结构的孔隙特征、颗粒特征和结构连结方式.基于ImagePro Plus图像软件,对人工冻融软土微观结构中的孔隙直径、孔隙圆形度、孔隙定向频率等微观结构参数进行定量分析.结果表明：在循环荷载作用下,土体孔隙结构具有压密趋势,土颗粒破碎程度加剧,小孔隙增多,大孔隙减少,孔隙变得更加规则,孔隙呈定向性分布.对于人工冻融土而言,不同的冻结温度和冻融周期对结构破坏程度有影响,从而导致动力特性的差异.冻结温度越低,冻融循环次数越多,在循环荷载作用下将表现出更明显的结构弱化效应.

英文摘要：

The micro-structure of the frozen thawed soil was tested by electron microscopic scanning with the freezing-temperature and freezing-thawing cycle as the control variables based on the construction of the Metro connection channel.Qualitative description of the pore characteristics,particle characteristics and structural connection of the micro-structure of the frozen thawed soil after GDS dynamic three axis loading was described.The micro-structure parameters such as the pore diameter,the roundness of the pore and the directional frequency of the micro-structure were quantitatively analyzed based on the ImagePro Plus image analysis software.Results showed that the pore structure of soil mass had the tendency of compaction under cyclic loading.The degree of fragmentation of soil particles was increased,the number of small pores was increased,and the number of big pores was reduced.The pore became more regular,and the pore was directional distribution.For artificial frozen thawed soil,the different freezing temperature and freezing-thawing cycles had an impact on the structural damage.Then the dynamic characteristics of the artificial frozen thawed soil were different.When freezing temperature decreased or the number of freezing-thawing cycles increased,the soil sample showed a more obvious structural weakening effect under cyclic loading.