The apparatus used for cyclic triaxial strength tests is somehow similar to the conventional triaxial test equipment used for the unconsolidated-undrained triaxial compression test and the consolidated-undrained triaxial compression test. The main key differences are as follows.

• wo linear ball bushings or similar bearings used to guide the load rod to minimize friction and to maintain alignment.
• A relatively large load rod diameter to minimize lateral bending (minimum load rod diameter of 1⁄6
  the specimen diameter).
• Very low friction piston seal
• Centeralized and well placed top and bottom plate
• Since in cyclic triaxial tests extension as well as compression loads may be exerted on the specimen, the load rod shall be connected to the top platen by straight threads backed by a shoulder on the piston that tightens up against the platen.
• Drainage at both top and bottom plates

The test involves subjecting a cylindr soil sample to cyclic axial load at undrained condition. Specimens shall have a minimum diameter of 51 mm with a height-to-diameter ratio between 2.0 and 2.5. The largest particle size shall be smaller than 1⁄6 the specimen diameter.

The specimen in vertically enclosed in a thin rubber membrane. The specimen preparation depends on the type of the soil. Samples of cohesive soils are often prepared directly from saturated compacted samples, either undisturbed or remolded. For cohesion-less soils, however, the specimen is prepared with the help of a mold that maintains the required shape of the specimen. 

After the sample measurement and first saturaion phase, the initial drainage loading is isotropically applied to a desired confining pressure. Following consolidation, the drainage values are closed and cyclic loading started.

The magnitude of cyclic load to be applied is estimated for the desired stress ratio. The desired stress ratio, SR, is the ratio of the desired deviator stress to double the effective consolidation
stress.

The cyclic loading is tarted with the first half cycle in compression using a 0.1 to 2 Hz sinusoidal load form where the stress varies between peak compression and peak extension values. During
cyclic loading, the cell pressure is kept constant and recordings are done for the axial load, axial deformation, and change in pore-water pressure with time.

The loading is continued until either the cyclic double amplitude vertical strain exceeds 20 %, the single amplitude strain in either extension or compression exceeds 2 %, 500 load cycles or the number of load cycles required in the testing program are exceeded, or the load wave form deteriorates beyond acceptable values.

Cyclic triaxial results includes the time histories of load, deformation and pore water pressure. The number of cycles required for a specimen to reach various values of double amplitude axial strain are often plotted versus the cyclic stress ratio (CSR). It is possible to normalize strength values of
specimens at a given density tested at a number of confining pressures. Such data from tests on the same material at the same density may be combined and plotted as CSR versus N (number of cycles) values, which are commonly called cyclic triaxial test strength curves.