Damage analysis of shear mechanical behavior of pile–structural soil interface considering shear rate effect

It is of great significance to investigate the shear mechanical behavior of pile–structural soil interface (PSSI) for guiding the design and construction of pile foundations in structural soft soil areas. The available studies rarely consider the effect of shear rate on the shear behavior of the PSSI under large deformation, and a relevant constitutive model is still lacking. In this paper, the effect of shear rate on the shear behavior of the PSSI under large deformation is investigated using a series of ring shear tests with different shear rates. Based on the test results, damage theory is introduced to analyze the mechanism of shear damage of the PSSI, and an interface damage constitutive model is proposed to describe the shear mechanical behavior of the PSSI under large deformation. Finally, a method for calculating the brittleness index of the PSSI is proposed based on the interface constitutive model. The evolution of the shear stress of the PSSI is analyzed, and the shear mechanical behavior of the PSSI under any normal stress is evaluated. The results show that the PSSI subjected to large deformation exhibits strain softening and has stable residual strength. The shear strength of the interface first decreases and then increases with increasing shear rate. The interface constitutive model can accurately reflect the shear behavior of the PSSI under large deformation. The shear rate has a positive effect on the brittleness index of the PSSI, and the normal stress amplifies this effect. The interface constitutive model can also predict the effect of normal stress on the brittleness index.