Abstract
A circular arc test is described 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 test method is simple and boundary conditions are well defined. 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 fiber-glass 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.