A unified model for sands and its application into geotechnical analysis

In the traditional modeling of the mechanical behavior of sand, different sets of model parameters are used to express sands that have different initial densities and confining stresses, despite the fact that the sands are of the same material. This approach complicated the calibration process. Furthermore, the approach in general cannot simulate realistically the entire range of loading history because of the change of the soil density during loading.; In this study, a generalized plasticity model was proposed for simulating the monotonic and cyclic behavior of sands that have different initial densities and confining stresses using a unique set of material parameters. The critical state concept was used in conjunction with the generalized plasticity. Liquefaction and cyclic mobility of saturated sands under undrained cyclic loading as well as densification behavior under drained loading were captured by the model. Extensive laboratory test results obtained in the literature were used for validating the model.; The proposed model was incorporated into a finite element program DIANA-Swandyne-II and used to simulate the horizontal soil deposits in the centrifuge models. The comparison between the numerical and experimental results showed good agreement. The results of simulation proved that the proposed model as well as the numerical procedure were relevant for studying the dynamic behavior of saturated sand deposit.; Four shaking table tests on the modular block geosynthetic-reinforced soil retaining walls (MB-GRS) were simulated using the proposed numerical procedure. The backfill and foundation soil was modeled using the proposed model and the behavior of the geosynthetics was captured by a one-dimensional bounding surface plasticity model. Reasonable agreement was achieved between the analysis and test results. The simulations showed that the numerical procedure can be used to study the behavior of geosynthetic-reinforced soil retaining walls under seismic loading conditions.