Strength properties of unloading confining pressure of long-term K₀-consolidated artifical frozen clay under high pressure

In most cases, the artificial ground freezing method has been applied to construction of vertical shaft in deep and thick alluvia. Thus the in-situ mechanical properties of deep frozen soils are the most pivotal influence factor to the stabilization of frozen wall. It is suspicious to acquire the mechanical parameters of deep soils by the methods which are suitable for shallow soils ignoring their engineering situation and origin. Therefore, based on the new test mode of "Long-term, K₀ consolidated- freezing-constant axial pressure and unloading confining pressure", many triaxial unloading tests are conducted on remolded deep clay so as to study its strength and deformation properties and the influence laws of consolidation stress and consolidation time. The research results show that the failure mode of the frozen clay specimens under unloading path belongs to the viscoelastic-plastic one. The strength of the frozen clay consolidated for 1 to 7 days under unloading path increases evidently, however, the growth rate of strength is barely affected by the consolidation time while temperature decreases. Conversely, the strength increases inconspicuously when the consolidation time is expended to 28 days. In addition, there is significant increase of growth rate of strength relating to the descending temperature in the process of the long-term K₀ consolidation. The influence of consolidated stress on the growth rate of strength hardly relates to the subzero temperature.