A Circular Arc Test for Soil-Geosynthetic Interface Strength

In many applications for geotextiles and geomembranes, knowledge of the frictional behavior between the soil and the geosynthetic is necessary for design. This paper describes a circular arc test for determining the residual, or constant volume, interface strength parameters between soil and geosynthetics. The model is based on the variation of tension in a circular arc of fabric placed over a soil specimen and dead-loaded on two ends. The boundary conditions are well defined in this simple test method. The apparatus, theoretical formulation, and testing procedures are presented. The interface friction angle between dry Muskegon sand and three different materials, a cotton fabric, a fiberglass mesh, and a nonwoven Geolon N35 filter, as determined by the circular arc test, are presented. Results of a staged circular arc test are also presented for the cotton fabric, and comparison to direct shear test results is made.