Deformation characteristics of the shear band of silty clay–concrete interface under the influence of freeze–thaw

Abstract

Direct shear tests of the silty clay–concrete interface under different moisture contents and freeze–thaw (F–T) cycles were conducted to study the mechanical and deformation characteristics of the silty clay–concrete interface under the action of F–T cycles. The change rule of shear band thickness under F–T cycles were analyzed based on particle image velocimetry technology. The microstructure changes of the damaged specimens were observed combined with scanning electron microscopy. Experimental results show that the shear strength of the silty clay–concrete interface is negatively correlated with the F–T cycles and moisture content. The moisture content increases from 12.7% to 20.7%, and the shear strength of the shear band decreases by 7.6%, 7.5%, 7.5%, 12.3%, and 10.5% after 9 F–T cycles, respectively. The shear strength of the shear band decreases obviously after 3 F–T cycles, and tends to be stable after 7 F–T cycles. The successive F–T cycles increases the thickness of the shear band until it stabilizes after 3 F–T cycles. The length and width of cracks inside the specimen increase as the number of F–T cycles rises. The orientation of particles in the shear band is weakened, but the orientation of particles in the shear band is always stronger than that outside the shear band. The change in soil particle and pore content is the most obvious in 3 F–T cycles, and it is the reason for the change in shear band.