A modified commercial triaxial testing system for small strain measurements: preliminary results on Pisa clay

A computer-controlled hydraulic triaxial cell was modified with the aim of obtaining (1) a better measuring accuracy of soil stiffness at small strains, (2) a reliable automatic procedure for K0 consolidation, and (3) a minimum disturbance during system saturation and specimen consolidation. To obtain the above objectives, many modifications were introduced. The cell structure and loading piston were modified and many transducers were introduced, including the LDTs for local radial and axial strain measurement. Finally, control software was developed to achieve the following testing procedures: (1) dry setting, (2) system saturation by flushing with stress control to avoid any swelling and back pressurization, and (3) K0 consolidation with control of nil radial strain by means of local measurement. The paper will benefit those interested in upgrading an existing hydraulic triaxial system in-house in an economical manner.