Unloading Creep Characteristics of Frozen Clay Subjected to Long-Term High-Pressure K0 Consolidation before Freezing

Abstract

Artificial ground freezing has been widely applied in the construction of vertical shafts in deep and thick alluvia. As an important factor, the in situ creep behavior of deep, frozen soil affects the mechanical properties of frozen walls and the safety and stability of shaft linings. Acquiring creep characteristics and deep soil parameters by methods that ignore the engineering and geological situations is currently inadvisable. A series of triaxial unloading tests were conducted with frozen clay subjected to long-term high-pressure K0 consolidation before freezing to research the unloading creep characteristics, creep strength, and other parameters of the clay, and the results indicated the following: (1) The creep behaviors of frozen clay are affected by the consolidation time and consolidation stress. Long-term high-pressure K0 consolidation reduces the creep strain and creep rate of frozen clay. (2) The decrease in the ice and the unfrozen water contents of frozen clay caused by the prolongation of consolidation time result in an increase in the long-term strength and instantaneous strength. Consolidation time has an obvious effect on long-term strength and weakens the creep property of frozen clay. Consolidation stress significantly affects the instantaneous strength. (3) The deformation resistance capability of frozen clay is enhanced by compaction; thus, E1, η1, and η2 increase with prolonged consolidation, and the nonlinearity of the accelerated creep increases.