中文摘要：

冻融作用通过改变土的结构性从而改变土的力学性质.以青藏粉质黏土为研究对象,对一定干密度的饱和重塑试样分别进行封闭和开放状态下的冻融试验.通过土样电阻率的改变来反映冻融作用对土中孔隙的影响;对冻融前后的试样分别进行CT扫描,定量分析土样的损伤程度,来反映土颗粒联结的改变.对冻融前后的土样进行不固结、不排水三轴剪切试验,得到其强度参数,并将冻融作用引起的结构变化与强度参数的变化建立联系.研究表明：对试验中采用的土样,经过冻融作用后电阻率增大,反映到强度参数上,冻融作用导致土的内摩擦角增大;CT扫描定量分析发现,经过冻融之后,密度增大,CT损伤量为负值,反映到强度参数上,冻融后黏聚力增加.因此,强度参数的变化与土颗粒的胶结和重排列,粒径重分配以及孔隙大小比例的变化有关.

英文摘要：

Structural change of soil due to freeze-thaw is the primary cause for the variation of mechanical properties.In this paper,silty clay from the Tibetan Plateau was taken as the research object for evaluating the structural change induced by freeze-thaw.The electrical resistivity of saturated remolded soil was measured for analysis of change of soil pore properties,while CT scanning of soil before and after freeze-thaw was carried out for quantitative analysis of the changes in bonding between particles.The strength parameters obtained by unconsolidated undrained triaxial（UU） tests were correlated with the resistivity and CT damage.It is found that the resistivity of soil increases after freeze-thaw due to the changes in pore distribution,which increase internal friction angle of soil.In the meantime,it is revealed that freeze-thaw leads to increase CT number and negative CT damage for all specimens.Correspondingly,the cohesion of specimens increases after freeze-thaw due to enhancement of bonding among soil particles.The variations of strength parameters are therefore closely related to the changes in bonding,redistribution of soil particles and the distribution ratio of porosity subjected to freeze-thaw.