Friction and energy dissipation along the interface between sand and construction materials

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This study concerns the behavior of interfaces between ground and structural foundation. Laboratory tests were carried out on the friction between sand and construction materials. Based on the results, analyzed were the factors influential to the frictional resistance. This study also includes an attempt to interpret the interface sliding as an energy dissipation process. Followings are conclusions of this study.Sand-steel coefficient of friction at yield varies with surface roughness of steel, median diameter and type of sand. Normalized roughness proposed is the ratio of the steel roughness in Rmax to the median diameter of sand. There are high correlations between coefficient of friction and normalized roughness.A shear zone formed along a rough interface due to the disturbance in sand fabric. There was no formation of a shear zone along a smooth interface under monotonic loading. When the interface slid repeatedly, a shear zone formed even along a smooth interface.When the interface was rough, the frictional resistance decreased with the increase in number of in cyclic loading. This is due to the formation of a shear zone along the interface. In case of smooth interface, the frictional resistance increased with loading number if particle crushing was significant along the interface. The frictional resistance converged to the value of maximum shear stress ratio of sand under repeated loading.Sand-concrete coefficient of friction varies with roughness of concrete and median particle diameter. The roughness evaluated by Rp rather than Rmax showed a high correlation with the coefficient of friction.At the yield of interface, plastic work along the interface become larger than that of sand mass. The energy dissipation along the interface is attributed to the slipping of interface, shear zone formation and the deformation of shear zone.