The aim of this thesis is the investigation of the cooling occurring in the rock surrounding dry mine roadways and the subsequent development of a method for the prediction of underground air temperature increases.
Strata cooling under different applied conditions is investigated using a series of closely controlled laboratory experiments conducted using a model arrangement which simulates actual cooling. From the results of the test work, a more complete understanding of the operating processes is obtained.
In particular, with the laboratory model, the effect of the air flow rate on strata cooling is thoroughly investigated. Little previous work has been performed to determine the influence of this parameter. Field work in addition to these investigations confirms the importance of this factor in the penetration of ventilation cooling into rock strata.
A novel means of reducing strata heat flow by use of artificial surface roughness is investigated.
Values of the thermal properties of specific rocks determined by an IN-SITU experiment are compared with those values obtained by application of laboratory methods to core samples of the rocks. While agreement is obtained between values determined by application of the different laboratory methods, the thermal values measured IN-SITU exhibit considerable variation. One method of analysis is found totally unsuitable for the reduction of the test results.
Field measurements for the determination of strata thermal properties, further emphasize the inaccuracies resulting from a particular method of analysis. A more acceptable method is developed.
From the results of the above investigations, a method is devised for the prediction of underground air temperature increases. The increases predicted by this method compare favorably with values predicted by other methods. On site difficulties prevent the direct comparison of measured and predicted air temperature increases. However, correlation is obtained between measured and predicted strata temperatures for the applied cooling conditions and this justifies the use of models for the investigation of strata heat flow.