Influence of initial confining stress on the quasi-steady state
Influence of initial confining stress on the quasi-steady state
In the laboratory, the minimum mobilized undrained shear resistance (at the quasi-steady state, QSS) of sand samples consolidated to the same void ratio (e) has been found to be dependent on the initial confining pressure (p'c). This non-uniqueness of the QSS is investigated in this paper using the DEM with the aim to understand its governing micromechanics. Similar to the experiments, the results of the numerical simulations showed a peak followed by a drop in the shear resistance to a minimum value at the QSS. Further shearing led to an increased regain of the shear resistance towards the steady state (SS). Up to the QSS, the rate of decrease of mean effective pressure and average coordination number increased with the decreasing p'c values. This can be attributed to the increasing proportion of sliding contacts with the decreasing p'c at a given axial strain which suggests the correspondingly increasing particle rearrangement at the QSS with the decreasing p'c. At the QSS, contacts between the coarser and finer sized grain fractions showed negligible contribution to the overall strength but this contribution increased with the increasing p'c.
Syed Uzair Us Salam Shah; Roberto Cudmani; Andres Pena-Olarte
10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)
2. Finite element, finite difference, discrete element, material point and other methods
https://doi.org/10.53243/NUMGE2023-261
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