Understanding of progressive failure in view of particle crushing and it's modelling

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This research consists of two parts; experimental and analytical. The following results were obtained. The experimental research includes 1.compression tests on a single particle, 2. One-dimensional compression tests, and 3. Loading tests on crushable model ground. A series of single particle tests revealed that there are three types of failure mode; split failure, shear failure and compressive failure, depending on the number of contact points and the relative magnitude of their contact forces. From the one- dimensional compression tests, it was observed that so-called pre-consolidation pressure is corresponding to 50 % of accumulated crushing ratio and the rate of time dependent settlement behavior become the largest at the pre-consolidation pressure, and also some jumping phenomena occur for a particular type of crushable materials. It was found from the loading tests that the time dependent behavior becomes more marked as the factor of safety for bearing capacity decreases, and the freedom of particle rotation plays an important role in determining the number of crushing particles and the zone of the crushing. DEM analysis was conducted by incorporating each particle having a number of its baby particle inside. The one-dimensional behavior was reasonably simulated if the model parameters were calibrated by the single particle test results. But the time dependent behavior was not fully simulated, suggesting that the model needs a parameter describing time dependent behavior.