Effects of stress path and grain size distribution on the mechanical behaviour of crushable granular material

The effect of the stress path and the initial grain size distribution on grain crushing was investigated on\ud artificial material of a sand grain size. The thesis consists of two parts. In the first part isotropic\ud compression test, oedometer test, conventional triaxial test (at constant cell pressure) and triaxial\ud compresion test with constant mean effective stress are analysed. For the purpose of the research\ud described in this part of thesis crushed artificial material known under commercial name Light\ud Expanded Clay Aggregate was used. Based on findings gained from the analysis a model describing\ud grain crushing and changing of internal friction angle was prepared. In second part of the research\ud different ways of crushing modelling were analysed. Two ways were then briefly tested. For the\ud approach that showed to be better describing grain crushing a complete model was prepared together\ud with all the measurements needed to track the sample behaviour during simulation. At the end the\ud model was tested. It turned out that the application of parallel bonds in modelling grain crushing is\ud unnecessary. The main reason for parallel bond application in the model was good description of\ud tensile grain failure. Due to the high coordination numbers the tensile grain splitting is unlikely to\ud occur. Instead, shear grain failure at contact is the most common grain failure. Therefore, contact\ud bonds, which are much more computationally efficient, should be used instead. The sample\ud preparation procedure with application of elementary particle expansion method turned out to be\ud unsuitable. Since for different grain size distributions with the same initial porosity, the stresses\ud induced with this procedure can vary significantly. Compaction of the sample layer by layer would\ud much better serve this task