The Relationship Between Roughness And Mechanical Properties Of Clay-Concrete Interface

The roughness of interface between soil and concrete structure has been one of the important research subjects of geotechnical engineering. This paper use the interface between red clay and concrete structure as the research subject, according large-scale shear test, focus on the relationship between roughness and mechanical properties of interface between clay and concrete structure, analyze the influence rule and explore the influence mechanism. The main achievements obtained in the test are as follows:1. This paper has done comparative study on the common methods to evaluate the roughness of concrete structure’s surface. And the results prove that the sand filling method is a better reasonable method. But when the sand filling method is used to evaluate the roughness of the concrete structure with the surface of the rule changes, it has some obvious disadvantages. This paper introduces two reduction parameters to revise it. The revised sand filling method is suitable to evaluate the roughness of the concrete structure with the surface of the rule changes.2. The smooth interface between clay and concrete structure is one of the special interfaces, so this paper has done detailed study on its mechanical properties. According to the test data, this paper summarizes the regular pattern of clay-concrete structure interface’s curve of shear stress-shear displacement, shear strength, the position of shear failure surface and normal deformation. The paper describes the curve of shear stress-shear displacement in two sections, before the maximum, we can use exponential model; after the maximum, we can use exponential model, and this paper comes up with a testing method to get the hyperbolic parameters. In the limit range of normal stress, the curve of normal deformation-normal stress can be described by exponential model.3. This paper has summarized the influence of roughness on mechanical properties of the interface between clay and concrete structure. The test results proves that as the roughness increases, the curve form of shear stress-shear displacement changes from the peak type to the broken line type, and then to the hyperbolic curve type. This paper points out that the maximum roughness of the interface between clay and concrete structure is dmax the affecting depth of clay. For the cohesion, the roughness of the interface between clay and concrete has one critical value, yncr. If0≤y<yncr, as the roughness increases, the cohesion increases, and we can use exponential model to describe it; If yncr≤y<dmax,the cohesion fluctuates around the cohesion of the clay. The friction of the interface is fluctuant, but not more than the friction of the clay.4. The reason why roughness influences the mechanical properties of the interface between clay and concrete structures is possibly that the dislocation and fracture between the clay around the surface of concrete structures. As the normal pressure increasing, the degrees of effects of the roughness decrease. In the actual projects, the normal pressure is not more than600kPa, so the effects of the roughness cannot be ignored.