| Tartalmi leírás: |
Understanding cyclic liquefaction as a progressive loss of solid-like contact connectivity requires a state variable that is measurable at the specimen scale but still interpretable at the grain scale. Following the order-parameter coined in physics, this paper uses the cycle-by-cycle decrease in apparent viscosity, obtained from the stress-shear-rate response, as a macroscopic descriptor of fluidization in saturated sand. The excess pore-pressure ratio is treated as the control variable, whereas the normalized apparent-viscosity degradation is interpreted as an order parameter-like variable that decreases as the load-bearing contact network is destroyed. A Landau-type free-energy argument is then connected to a granular-scale, bond-frustrated connectivity model, giving an explicit expression for the order-parameter evolution with pore-pressure ratio. The model is calibrated only on one reference void ratio and is then used to predict the other void-ratio cases with the same fitted coefficients, so the comparison tests transferability rather than independent curve fitting. For Ottawa F-65 sand with initial void ratios of 0.515, 0.542 and 0.585, the predicted responses follow the measured apparent-viscosity degradation with R2 values of 0.95, 0.98 and 0.94, respectively. The result supports the use of apparent viscosity as an experimentally accessible order parameter for constitutive augmentation, rather than as a replacement for effective-stress models.
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