An Injection-Correction System to Mitigate Membrane Compliance
A computer-controlled injection correction system has been developed to continuously mitigate the adverse effects of membrane compliance for undrained testing of granular soils. The system was developed with the explicit idea that it could be quickly and easily adapted to almost any up-to-date triaxial testing apparatus. Methodology of the system is based on the direct and repeatable relationship between effective confining stress and volumetric compliance. A closed loop computer-controlled system continuously monitors changes in specimen effective confining stresses such that precalculated volumetric compliance errors may be continuously offset by injecting or removing volumes of water equal to those errors throughout the duration of each test. Implementation of the injection-correction system was demonstrated for a uniformly graded medium sand, exemplifying the potential usefulness of such a system.