Experimental Study On Strength Characteristics Of Interface Between Qinghai-Tibetan Frozen Silt And Building Materials

±400kV DC interconnection project will be-built from Qinghai to Tibet for supporting economic and social development and guarantee energy supply in Tibet. This project will across permafrost and deep seasonally frozen ground regions in the Qinghai-Tibet plateau, which is more than1100km from Golmud in Qinghai province to Lhasa in Tibet. Among which the permafrost regions is about630km long and deep seasonally frozen ground regions is bout470km long.External load will limit and impact the frost deformation of foundation soil because of building structures. Then the deformation, displacement and damage will happened in building structure because of frozen-heave force. There are three kinds of frozen-heave force between foundation of building and soil:horizontal frost-heave force, normal frozen-heave force and tangential frost-heave force. Tangential frost-heave force is perpendicular to frozen frontal surface and is parallel to side surface of foundation which is a pulling force make foundation move as the frost heave deformation of soil. To mitigate the effect of frost heave, a countermeasure of fiberglass reinforced plastics (FRP) covering was put forward and applied to the foundation engineering of Qinghai-Tibetan transmission line. There is limited information involved in the mechanical properties of the interface between frozen soil and foundation. A series of laboratory direct shear tests of the interface between silt and concrete or silt and FRP plate are performed. Based on the stress and shear displacement relation of the interface and standard modeling method, a stress-displacement-temperature constitutive equations of the interface was presented to describe the mechanics behaviors of the adfreeze interface. Experimental results validated that the constitutive model can reasonably describe the stress-displacement relationships for different temperatures. The constitutive relation can be used in the numerical simulation of stress and deformation of the structures in cold regions.