Accumulative Plastic Deformation And Critical Dynamic Stress Of Frozen Silt Clay In Permafrost Region Under Cyclic Loading

Accumulative plastic deformation and critical dynamic stress of frozen soils under cyclic loading are of importance in practice to the railroad design in permafrost regions. In this study, a series of dynamic cyclic tri-axial tests were conducted on frozen silt clay along the Qinghai-Tibet Railway to explore the accumulative plastic deformation and critical dynamic stress of frozen soil induced by cyclic loading. Particularly, the dynamic cyclic tri-axial tests were carried out under circumstances of different frozen temperatures ranging from -0.5 degrees C to -11 degrees C. Based on the test results, an analytical model is developed for describing the relationship between critical dynamic stress and the freezing temperature. Furthermore, the experimental test results revealed the following mechanical behaviors of the frozen silt clay: (1) the permanent strains increase with rising the temperature, the vibration numbers and the dynamic stress amplitude. (2) The freezing temperature has obvious effect on the permanent strain with the dynamic stress amplitude increasing. (3) The critical dynamic stress increases as freezing temperature falls. All the above results play an important role for further understanding the dynamic behaviors of Qinghai frozen soil under repeated cyclic loading and providing the fundamental parameters for railway embankment design and the long-term reliable operation in frozen soil regions.