Abstract: In order to analyze micromechanism and coupled behaviors of consolidation and creep of soft clay, the consolidation and creep test at different drainage conditions and different consolidation pressures and the scanning electron microscopy test of the undisturbed sample and sample after creep are carried out from soft clay in the Yellowstone region. The results show that the creep behaviors under undrained condition are even more significant compared with under drained condition. Under lower bias stress condition, the deformation under drained condition is larger comparatively and with the opposite conclusion under higher bias stress condition. The deformations under drained condition are induced by consolidation and creep which have linear creep properties; and the deformations under undrained condition are induced mainly by creep which has nonlinear creep properties. The particle distances and large pores are reducing and small pores are increasing with the transition from side - side, side - surface to surface- surface of particles contact form during creep process. The bound water with the form of penetration absorption is changed mainly into free water to excrete during consolidation process and the creep process is mainly controlled by bound water. With increasing pressure and decreasing pore volume, the hydrated film is thin to increase the viscosity of soil which takes on the behavior of creep in the long term. The drainage performance in soft-soil reinforcement can be improved to increase the consolidation degree of soil which can reduce the harms brought by creeping and improve the stability of building.

Key words: soft clay, consolidation-creep, drainage condition, creep mechanism, bound water