Volume 35, Issue 6 (November 2012)
Performance and Suitability of Radial Drainage Materials in Axisymmetric Testing of Clayey Soils at High Confining Pressures
When lubricated end platens are used in axisymmetric testing of clayey soil specimens, radial or side drainage is often used. As confining pressure increases, the filter paper rapidly loses its flow capacity. An experimental study of different radial drainage materials in compression and extension is presented examining their flow capacity and vertical load corrections at confining pressures ranging from low stresses to approximately 3000 kPa. Drainage materials investigated include filter paper and various non-woven geo-textiles. At high pressures, flow capacity was greatly limited by clogging, thereby limiting the allowable strain rate for drained tests. The vertical load carrying capacity of drainage materials in different configurations (vertical strips or sheets with inclined slots) was determined to be much higher than expected, even for filter paper.