Inspection of a high-cycle accumulation model for large numbers of cycles (N=2 million)

• Results from 13 long-term drained cyclic triaxial tests with 2 million cycles are presented.
• The cyclic flow rule of the HCA model could be confirmed up to N=2·106N=2·106.
• The function fN of the HCA model could be confirmed up to N=2·106N=2·106.
• HCA parameters from tests with N=105N=105 overestimate residual strains at larger N.
• Correlations for a simplified calibration procedure have been revised for 2 million cycles.

The high-cycle accumulation (HCA) model for sand proposed by Niemunis et al. (2005) [16] has been developed based on numerous drained cyclic triaxial tests with 100,000 cycles. In the present paper the validity of the HCA model, in particular its function fN and flow rule m, for larger numbers of cycles is inspected. For that purpose, drained long-term cyclic triaxial tests with 2 million cycles have been performed on 13 clean quartz sands with different grain size distribution curves. For all tested sands, the function fN, describing the shape of the strain accumulation curves εacc(N)εacc(N), has been found suitable up to 2 million cycles. The same applies to the cyclic flow rule m, determining the ratio of the volumetric and deviatoric strain accumulation rates. Based on the data from the long-term tests, correlations between the HCA material parameters entering fN and characteristics of the grain size distribution curve (d50 and Cu) have been improved for the application to 2 million cycles. These correlations are suitable for a simplified calibration of the HCA model and were validated up to 100,000 cycles only so far.