Vertical Load Corrections for Two Side Drainage Materials in Laboratory Testing of Clays

When lubricated end platens are used in axisymmetric testing of clay specimens, radial or side drainage is often used. An experimental study of different radial drainage materials in compression and extension that examines vertical load corrections at confining pressures ranging from low stresses up to approximately 3,000 kPa is presented. As confining pressure increases, the filter paper rapidly loses its flow capacity. Therefore, the drainage materials investigated include filter paper and various non-woven geo-textiles which maintain their flow integrity at higher pressures. 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.