Material characteristics. 2.1.3.1. The cell dimensions shall be 19 mm ± 10 per cent for each block (see Figure 4).
Material characteristics. 2.3.2.1. The back plate shall consist of a 3 mm aluminium sheet. The back plate shall be manufactured from aluminium of series AlMg2 to AlMg3 with hardness between 50 and 65 HBS. This plate shall be perforated with holes for ventilation: the location, the diameter and pitch are shown in Figures 5 and 7.
Material characteristics. 2.2.2.1. The front plates are manufactured from aluminium of series AlMg2 to AlMg3 with elongation ≥ 12 per cent, and a UTS ≥ 175 N/mm2.
Material characteristics. The material of the impactor must be an aluminium honeycomb. Other materials can be used if equal results as described in
Material characteristics. 2.2.2.1. The front plates are manufactured from aluminium of series AlMg2 to AlMg3 with elongation 12 per cent, and a UTS 175 N/mm2. The material of the impactor must be an aluminium honeycomb. Other materials can be used if equal results as described in paragraph 2.3. have been proved to the satisfaction of the Technical Service. In any case the type of impactor must be indicated in the test report.
Material characteristics. Rock Mass Because all rock masses are more-or-less fractured, choosing the ‘best’ analysis approach has important implications for the design of stable underground openings. Although general guidelines (e.g., Xxxx and Brown9) exist for determining whether it is reasonable to characterize a rock mass as a continuum or discontinuum, the choice should be decided based on the prevailing rock mass conditions and the configuration of the underground (FLAC-ish). Table I summarizes the material parameters used for the M-C and S-S models, while Figure 2 shows a schematic of the stress-strain relations used for the S-S models. Rock Bolts and Shotcrete The rock bolts were modeled using FLAC’s bolt structural elements. These are 1D elements of elastic-perfectly- plastic response that also allow for bond failure between the bolts and the rock. Table II lists the rock bolt parameters used in these analyses. The shotcrete was modeled using FLAC’s beam structural element, and modified to include the nonlinear response associated with local failure from the combined axial and flexural loads in Eq. 4:
