Volume 25, Issue 1 (March 2002)
A Triaxial and Oedometer Apparatus for Testing Unsaturated Soils
The paper describes a new system for testing unsaturated soils designed at the University of Naples Federico II. The system is modular and can be configured either as an oedometer or a triaxial cell. Triaxial specimens are 68 mm in diameter and 140 mm in height, and oedometer specimens have a diameter of 56 mm and a height of 20 mm. The suction control is based on the axis translation technique. Radial strains are determined by an accurate measurement of the difference in pressures between the water filling an inner cell coaxial to the sample and that filling a reference double-walled burette, submitted to the same pressure. The water content variations are determined by measuring the difference in pressure in two double-walled burettes, one of which being connected to the drainage circuit, the other one operating as a reference. The calibration of all the devices, as well as their precision and accuracy, is widely discussed in the paper. Finally, the results of tests performed on an unsaturated pyroclastic soil are presented in order to highlight the features of both apparatuses.