IN-SITU DETERMINATION OF THERMAL PROPERTIES OF COAL MEASURE ROCKS IN UNDERGROUND COAL MINES

摘要

All the mathematical models for mine climate prediction are based on the numerical values of thermal properties of associated rock formations. Among them thermal conductivity and thermal diffusivity are important parameters and requires special attention. In the present paper a simple method of in-situ measurement of thermal conductivity and thermal diffusivity in coal mines is discussed. Thermal conductivity measurements were taken at five locations in four collieries in different seams. From these measurements average calculated values of in-situ effective thermal conductivity are presented. Existing methods of in-situ determination of thermal diffusivity are critically reviewed. A new method based on cooling of rock, instead of heating, is presented. Formulae have been derived to determine thermal diffusivity of rock massif from only nine temperature measurements in a single drill hole. However, for accuracy more measurements are recommended. A simple computer programme is described which requires negligible amount of computer memory space. Program output consists of number of diffusivity values calculated, their mean, standard deviation and range. An example from actual field measurement is also given.