An Alternative Shear Strength Test for Saturated Fine-Grained Soils: Preliminary Results

A proper definition of the effective shear strength parameters is a major concern for long-term evaluation of loads on fine-grained soils. The most common technique to measure such entities is the conventional triaxial shear (3X) test. Numerous researchers outlined the limitations, uncertainties and operator effects pertinent to this test. Furthermore, the consolidated 3X tests take extremely long time to complete. Recently introduced in soil mechanics, the reverse extrusion (RX) test was shown to be capable of measuring the undrained shear strength of fine-grained soils with a reasonable degree of success. The hypothesis of our investigation is that the RX test should also be able to provide drained (or effective) strength parameters if it is facilitated to measure the pore-water pressure (PWP). A new instrument was developed for this purpose. Three remolded soil samples were tested using both the conventional 3X and RX tests. A comparison between the effective internal frictional angles from 3X-CU tests and the effective extrusion pressures from the RX test test reveals a remarkably good match. The investigation is in progress to increase the number of remolded soil samples and to extend the research to include natural soil samples.