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The safety of cracked concrete dams is fundamentally affected by the mechanical behaviour of the material under cyclic loading conditions. In this case the crack can grow at a lower load level compared to the monotonic case. This phenomenon is called subcritical crack propagation and depends on the mechanical behaviour of the fracture process zone. To assess this phenomenon, a number of experimental tests, where the loading process is based on a first monotonic step (stopped before reaching the peak load), followed by a series of cyclic loading phases until collapse, are examined. The results of numerical analyses appear to be in good agreement with the experimental data obtained in the case of wedge splitting tests. [ABSTRACT FROM AUTHOR]

This paper introduces a three-dimensional model for simulating dense-snow avalanches, based on the numerical method of cellular automata. This method allows one to study the complex behavior of the avalanche by dividing it into small elements, whose interaction is described by simple laws, obtaining a reduction of the computational power needed to perform a three-dimensional simulation. Similar models by several authors have been used to model rock avalanches, mud and lava flows, and debris avalanches. A peculiar aspect of avalanche dynamics, i.e., the mechanisms of erosion of the snowpack and deposition of material from the avalanche is taken into account in the model. The capability of the proposed approach has been illustrated by modeling three documented avalanches that occurred in Susa Valley (Western Italian Alps). Despite the qualitative observations used for calibration, the proposed method is able to reproduce the correct three-dimensional avalanche path, using a digital terrain model, and the order of magnitude of the avalanche deposit volume. [ABSTRACT FROM AUTHOR]

The paper analyses the interaction between strain-softening and time-dependent behaviour in the case of quasi-static fracture of concrete. A viscous element based on a fractional order rate law is coupled with a micromechanical model for the fracture process zone. This approach makes it possible to include a whole range of dissipative mechanisms in a single rheological element. Creep fracture in mode I conditions is analysed through the finite element method, the cohesive (or fictitious) crack model and a new space and time integration scheme. The comparison with creep tests executed on three-point bending conditions shows a good agreement. [Copyright &y& Elsevier]