A Survey of Soil-Reinforcement Interface Friction

The most important aspect of reinforced earth is the sliding shear resistance between the soil and reinforcements expressed in terms of a sliding friction angle or a coefficient of friction. A number of different procedures have been followed in order to quantify this physical property and as a result there is a wide range of reported values. In the present paper, the friction coefficient values of smooth and rough brass strips as determined by modified direct shear tests and by pull out and wall rotation tests in a model box are given and interpreted. For smooth strips, it is found that direct shear and pull out tests give comparable results and the friction coefficients are not influenced by the density. For rough strips, however, pull out tests may give much higher friction values than the direct shear tests as density increases. In wall rotation tests which are an attempt to represent the friction mobilization mechanism in reinforced earth, the friction coefficient values appear to be limited by the values obtained from direct shear tests for both smooth and rough strips, irrespective of density.