INSTRUMENTATION FOR TORSIONAL SHEAR/RESONANT COLUMN MEASUREMENTS UNDER ANISOTROPIC STRESSES

Instrumentation for torsional shear/resonant column testing under anisotropic stresses has been developed. The test apparatus discussed is capable of torsional shear and resonant column testing with anisotropic states of stress applied to the soil specimen. Low-frequency torsional shear measurements are made using proximity probes to measure the angle of twist of the soil specimen. High-frequency measurements are made using conventional resonant column techniques adapted for use with an anisotropic loading system. Methods used for reduction of test data and calibration procedures are described.