| Popis: |
The behaviour of a hard rock horizontally stratified roof, within a low primary lateral stress field, is investigated. The lowest roof stratum is modelled as a voussoir beam with three cracks, one at the midspan and one at each abutment. Its response in bending is computed, with the help of a distinct element computer code, for an ordered series of configurations. Two states of failure, i.e. buckling and crushing, are examined. The parameters of indeterminacy of the structure are investigated numerically and improved relations are derived for their evaluation. From the solution of the determined structure, deflections, strains and stability limits are evaluated analytically and validated numerically. Finally, in order to check against crushing, a chart is provided for the prediction of the lateral non-linearly distributed axial strain at the extreme fibre of the abutment. |
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