Jilin Qi
State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and
Engineering Institute, Chinese Academy of Sciences

With the more and more constructions in cold regions, it is necessary to study freeze-thaw related geotechnical problems for the sake of infrastructures, so as to guarantee their stability. Frost heave, thaw settlement and freeze-thaw induced changes in mechanical properties are all freeze-thaw related problems. Frost heave has been extensively studied. Various theories have been put forward to describe the mechanism of ice segregation which is considered as the main cause of frost heave; and some theories have even been applied to quantitative analysis. The study of thaw settlement has a long history, many previous studies have used empirical relationships. In the last 30-40 years, thaw consolidation has been studied. This presentation will focus on freeze-thaw induced changes in engineering properties of soils, which considers freeze and thaw as a whole process and it is far lagged behind the studies on single process, i.e., frost heave or thaw settlement. A brief state-of-the-art of this study will be firstly presented and concluded that more soil types, wider range of density as well as freeze-thaw conditions should be considered in the next step. Testing program has been designed so as to reflect these factors. Stored free energy has been applied in analysis of the testing results, which set up a primary basis for modeling.