Centrifuge model studies on the stability of fibre-reinforced cemented paste backfill stopes

Cemented paste backfill (CPB) is used extensively in Australia for providing ground support during underground mining operations. This paper considered the use of polypropylene fibres to reinforce the partial or whole body of CPB models in laboratory centrifuge tests. Specimens were cast as non-reinforced (tailings, cement and water), quarter-height, half-height and full height fibre-reinforced CPB model stopes. The stability of CPB models with vertically exposed faces was investigated by a series of centrifuge tests. The modelling data showed that the prototype height of fibre reinforced CPB stopes could be much higher than that of unreinforced stopes depending on the extent of reinforcing. The vertical displacement and failure mass ratio of CPB models were also compared and discussed. The distinct failure modes showed that fibre reinforcement was effective in preventing the CPB failing into the strong box. Furthermore, virtually no fragments were spalled from the exposed faces of reinforced sections of the stopes. It indicated that the application of fibre reinforcement would potentially reduce ore dilution and recovery costs, because the risks of failure would be lowered and prototype stope sizes be enlarged.     

Trains of thought on the tabletop: visualizing association of ideas improves creativity

According to the Search for Ideas in Associative Memory theory, ideas in a brainstorming session do not come one by one but rather in “trains of thought,” which are rapid accumulations of semantically related ideas. In order to visualize these trains of thought, we developed a brainwriting tabletop interface enabling users to link successive ideas together by means of graphical ropes. To test the effectiveness of this device, 48 participants (in groups of four) brainstormed for 20 min on the tabletop in one of two conditions: either with the train-of-thought interface (with graphical ropes), or without the ropes (control condition). The results show that visualizing the associations between ideas enabled the participants to produce longer trains of thought. We also assessed originality by collecting the unique ideas in the whole corpus of ideas produced by the different groups and observed that the train-of-thought condition produced more original ideas than the control one. One interpretation of this finding is that visualizing trains of thought increases cognitive stimulation, i.e., improves creativity by making others’ ideas more intelligible to the brainstorming partners, in comparison with the classical visualization of ideas as independent items.