Improved simplified calibration procedure for a high-cycle accumulation model. Issue 70 (March 2015)

• Record Type: Journal Article
• Authors: Wichtmann, T.; Niemunis, A.; Triantafyllidis, T.
• Is Part Of: Soil dynamics and earthquake engineering. Issue 70(2015:Mar.)
• Page Start: 118
• Page End: 132
• Publication Date: 2015-03
• Subjects: Drained cyclic triaxial tests -- Quartz sand -- High-cycle accumulation model -- Simplified calibration -- Correlations; Soil dynamics -- Periodicals; Earthquake engineering -- Periodicals; Sols -- Dynamique -- Périodiques; Génie parasismique -- Périodiques; 624.176205
• DOI: 10.1016/j.soildyn.2014.12.011
• Languages: English
• ISSNs: 0267-7261

Abstract

Abstract: The high-cycle accumulation (HCA) model proposed by Niemunis et al.[16] predicts permanent deformations due to a drained cyclic loading with many small cycles (i.e. N ≥ 10 3 cycles with strain amplitudes ε ampl ≤ 10 − 3 ). The strain amplitude is the most important influencing parameter of the rate of strain accumulation ε ̇ acc . Based on tests on a medium coarse sand, a square relationship ε ̇ acc ~ ( ε ampl ) 2 has been used in the HCA model so far. The new test results presented in this paper indicate, however, that the exponent of the amplitude-dependence may vary between 1.3 and 2.4, depending on the tested material. This comes out of 150 drained cyclic triaxial tests with 10 5 load cycles performed on 14 clean quartz sands with specially mixed grain size distribution curves. Consequently, an additional material constant C ampl has been introduced into the HCA model describing the amplitude dependence according to ε ̇ acc ~ ( ε ampl ) C ampl . The additional parameter requires a revision of the simplified calibration procedure proposed by Wichtmann et al.[24] which uses correlations between the HCA model parameters and granulometric ( d 50, C u ) or index properties ( e min ). Furthermore, the new cyclic test data reveal that the existing correlations are inappropriate for well-graded granular materials ( C u ≥ 5 ). Enhanced correlations suitable also for more well-graded sands are proposed in the paper. The possible error of a HCA model prediction with parameters fully or partly determined from the correlations is discussed. Abstract : Author-Highlights: Results from 150 drained cyclic triaxial tests with 10 5 cycles on 14 sands are presented. The amplitude function of the HCA model has been revised introducing an additional material constant. The parameters of the revised HCA model have been calibrated for 22 sands. A simplified calibration procedure for the HCA model has been revised. The new correlations deliver a more accurate prediction for well-graded granular materials.