Experiment study on effects of freeze-thaw cycles on adfreezing strength at frozen soil-concrete interface

In order to study the effects of freeze-thaw cycles on the adfreezing strength between frozen soil and concrete interface, a series of direct shear tests are conducted with different numbers of freeze-thaw cycles under different normal stresses, test temperatures and initial water contents. The peak shear strength, residual shear strength, shear strength parameters are used to analyze the adfreezing strength at the interface. The test results show that the shear behaviors of the interface are still strain-softening after 20 cycles. The influences of freeze-thaw cycles on the peak shear stress are stronger than those on the residual shear stress, indicating that they have an effect on the content of ice crystal of the interface. When the water content of the soil is low and the test temperature is high, the peak shear strength lightly increases with the increasing cycles, and it decreases obviously at water content of 20.8% and test temperature of -5℃. Therefore, it is necessary to pay attention to the influences of freeze-thaw cycles on the peak shear stress under high water content, low test temperature and small deformation of the structural interface. The cycles have few influences on the residual shear stress. The peak cohesions of the interface increase, become stable and decrease with the increasing cycles at the test temperature of -1℃, -3℃ and -5℃, respectively, which is presumed to be caused by the water migration of the soil near the interface. The peak and residual interface friction angles are influenced slightly by the cycles.