Study on dynamic shear characteristics of frozen clay-concrete interface

The dynamic shear characteristics of the interface between frozen soil and concrete have a direct impact on the seismic stability and long-term serviceability of frozen soil engineering. In order to study the pile-soil interaction and freezing strength characteristics of pile side in permafrost regions under dynamic load, a dynamic direct shear system was developed based on the conventional direct shear instrument. It could meet the dynamic load output and low temperature control conditions at the same time. Using this equipment, dynamic shear tests of frozen clay-concrete pile foundation interface under different influencing factors were carried out. The effects of test temperature, normal pressure, dynamic load frequency and vibration times on frozen strength of frozen soil-concrete interface under dynamic load were studied. The change law of residual strength after interface shear failure was discussed. The test results show that under dynamic load, the mechanical behavior of frozen clay-concrete interface is characterized by strain softening. It can be obviously divided into four stages, which are linear growth, brittle failure, strength recovery and residual stability. The peak strength and residual strength of the interface are most significantly affected by the temperature change, and the dynamic load characteristics have a certain regularity influence on the interface strength. Temperature mainly affects the shear strength and residual strength through the action of ice cementation force. With the decrease of temperature, the interfacial cohesion significantly increases, thus showing the increase of freezing strength. By analyzing the strength characteristics of the interface between frozen soil and concrete under dynamic load, the characteristics and formation mechanism of the interface freezing strength are clarified. The results can provide reference for the research of shear characteristics between frozen soil and pile foundation interface and the prevention of frost-resistant pullout disease of structures in cold region engineering. © 2022, Central South University Press. All rights reserved.