Abstract:

In order to explore the interfacial shear properties between silty clay and concrete in seasonal frozen soil area, the freeze-thaw cycles test and the interface direct shear test of silty clay-concrete binary with different freeze-thaw cycles, normal stress and moisture content of soil were completed, and the changes of interface shear strength, shear strength parameters and shear strength damage degree were discussed. Through direct shear tests, the variation rules on shear properties of the interface and strength parameters were investigated. The results showed that the strain-stress relation underwent strain hardening phenomenon, which can be divided into elastic deformation stage (0-3 mm) and elastoplastic deformation stage (4-15 mm). The freeze-thaw cycles deteriorated the interfacial shear strength, that is, by causing damage to the soil, the friction angle and cohesion of interface were reduced, thereby reducing the interfacial shear strength. With the increase of the number of freeze-thaw cycles, the damage degree of interfacial shear strength increased. However, when the freeze-thaw cycles were 0 and four times, the shear strength damage was rapid, and the damage was slow when the freeze-thaw cycles were 12-20 times, in which the maximum interfacial shear strength damage degree was 25%. With the increase of moisture content of soil, the increase of moisture content of soil weakened the shear strength, the friction angle of interface decreased, however the cohesion first rose and then reduced. When the soil moisture content was 20.7%, the cohesion reached the maximum. The rising of normal stress enhanced the shear strength.

Key words: concrete, silty clay, interface, shear properties, freeze-thaw cycles, shear strength, seasonal frozen soil area