Cyclic Triaxial Test System

The cyclic triaxial test method can be used to A) determine the modulus and damping properties or B) the cyclic strength (or liquefaction potential) of soils. Following saturation and consolidation, the specimen is subjected to a sinusoidally varying axial load by means of the load rod connected to the specimen top platen. With time, the cyclic load, specimen axial deformation and pore water pressure development are monitored. The cyclic loading generally causes an increase in the pore-water pressure in the specimen, resulting in a decrease in the effective stress and an increase in the cyclic axial deformation of the specimen. Failure may be defined as when the peak excess pore water pressure equals the initial effective confining pressure, full or 100% pore pressure ratio (sometimes called initial liquefaction), or in terms of a limiting cyclic strain or permanent strain.

The test is conducted to approximate field conditions during earthquake or other dynamic loading (ocean waves, blasts, etc.).