Experiment in controlling stability of scarpment benches in deep-pit northern mines by means of foamed plastic heat-insulating shields

Conclusions

1. Foamed plastic has been applied in an experiment on benches of a mine with low temperatures in the experimental section. As a result of observations of the temperature field in this section, the following points have been established:

• •When the thermal insulation is present, the temperature at a depth of 2 m remains below freezing along the entire line of the bench (−0.9°C in the summer).

• •Without thermal shielding, the temperature approaches 0°C along the line of the bench at a depth of 2 m. This sort of situation should be regarded as critical, since conditions for rock cave-in are created, and the upper part of the bench is the most hazardous.

2. The experimental results have provided a basis for adapting a mathematical model of the dynamics of temperature change in a massif as a consequence of heat exchange with the atmosphere when the surface is covered with a heat-insulating layer of variable thickness. Comparisons show that the results obtained on the basis of adapted models make it possible to reduce the scatter of data by an average factor of 2.6. On the basis of computer experiments, a method has been developed for selecting parameters of thermal insulation with variable thickness.

3. For conditions of the Mir mine, with due consideration for the exposure of the slope, parameters of variable-thickness thermal insulation have been defined, with which a material saving of 13–20% can be realized.