Risk assessment of underground coal fire development at regional scale

Underground coal combustion is a phenomenon known worldwide. Coal fire monitoring and risk assessment provide important input data for the delineation of coal fire zones and planning of extinguishing activities. At present, research on coal fire risk focuses mainly on the probability assessment of spontaneous combustion at micro scale, based on laboratory investigations of coal molecular structure and composition, and their impact on the combustion process. Coal fire risk assessment at a larger scale, such as for mines, relies on geological factors and aspects of mining engineering and mine management. These scales, however, are insufficient when considering extinguishing activities in larger areas. In order to fill these gaps, we studied risk assessment of underground coal fire development (UCFD) at a regional scale.The factors impacting on coal fire development were analyzed under three different aspects: coal composition and structure which can influence the direction of underground coal combustion; topography and geology which determine the burning environment; and climatic conditions and human activities which trigger combustion processes. Based on this analysis, a regional underground coal fire risk assessment (UCF-RA) index system was established; it is predicated on the assumption that all indices contribute equally to coal fire risk. Data layers of 1 km × 1 km spatial resolution for each index were calculated and overlaid. Xinjiang Uygur Autonomous Region was selected as a validation area. In view of local conditions and the availability of relevant data, the index system was modified; the applied method, however, remained unchanged. Assessment results are generally satisfying and can be used for monitoring and extinguishing of underground coal fires (UCFs) in Xinjiang.

Research Highlights
► The factors impacting on coal fire development were analyzed based on the mechanism of fire combustion, a regional underground coal fire risk assessment (UCF-RA) index system was established based on the analysis.
► Assumption that the impact of each group of indices on coal fire development is of equal value. This is an objective approach in the absence of actual weights, and makes the comparison of the assessment results possible at a regional scale.