Features of Coal-bearing Strata Rock Thermal Conductivity and Influence on Heat Hazard in North China

The features of coal-bearing strata thermal conductivity were analyzed through data reduction and testing for different lithology rock samples in coal-bea ring strata of North China.The results showed that rock thermal conductivity was controlled by mineral composition, the thermal conductivity of sandstone, sandy mudst one, mudstone, carbon mudstone and coal decreased in turn with the shale contents increased.The higher the degree of metamorphism was, the higher the thermal con ductivity would be.In addition, thermal conductivity decreased commonly while the porosity increased.Strata combination of different lithology could control the vertical g eotemperture distribution.In the strata with lower thermal conductivity, such as coal seam and mudstone, the thermal gradient would be high resulting in local high temp erature environment. Studying on the vertical variation law of thermal conductivity was the foundation to forecast geotempreture field of deep coal mine and ensure the h eat hazard position.