Comparisons of the prediction methods for ground failure and construction of the DATA-BASE of those methods.

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In this study, a series of stability analyses and deformation analyses were carried out by using several kinds of failure prediction methods. The main conclusions drawn from these analyses are summarized as follows.1. A series of coupled stress-flow analyses for the bearing capacity and plastic flow of a rate-sensitive, saturated clay have been made using the method of finite elements. The undrained bearing capacity of the clay foundation increases with increasing loading rate, in accordance with the associated increase in the shear strength of the clay element. Indeed, the bearing capacity factor, <N_c> , remains at a practically constant value irrespective of the loading rate. The remarkable redistribution of stress occurs within the foundation clay undergoing creep under constant loads. This phenomenon prolongs the moment of possible failure of the foundation clay much more, as compared with the fictitious case where the shear stress in the soil mass would have been maintained constant during the creep process.2. By introducing new material functions and internal variables into the viscoplastic flow rule, we could establish a viscoplastic constitutive model for normally consolidated clays. This model can describe time-dependent behavior such as the strain-rate effect on the stress-strain behavior and creep rupture including acceleration creep.3. The monitored performance of a composite breakwater has been discussed, in the light of the during-event predictions using the method of finite elements. The stability ensured during the construction stage is most clearly reflected in the low value of the ratio between maximum lateral displacement and caisson settlement. The undersea measurements of settlements have provided a set of useful information, whereby two-dimensional nature of the ground deformation can clearly be identified through the settlement profile.