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Airflow reverse is a severe problem in an underground ventilation system. In addition, the airflow stability and safety production can be seriously affected by the problem of air velocity overrun in the roadways. In this study the crucial causes of the ventilation problems in a coal mine case study are analyzed and a solution is proposed through an analytical methodology. Measurements indicate high air resistance in the shaft and low values in the maintenance roadway, generating abnormal airflow directional behaviors. Strategies to solve the ventilation-related problems have been proposed and implemented, verifying normal ventilation conditions.

An airflow distribution in an ventilation network is changed when an airway resistance in the network is changed by an airflow regulator damaging or an airway collapsing. The occurrence of an abnormal airway will be found by analysing the airflow changes created in the network, if airflows are monitored in several airways. This paper describes the newly developed methods to locate an abnormal airway and estimate the changed value of resistance by means of analysis of the measured airflow data.In the first method the ventilation network is analyzed, measured airflow data being introduced, and the pressure distribution thereby obtained are examined, which enables us to detect the place creating an abnormal airflow resistance and to evaluate the change.The second method utilises a data base of airflow distributions which are calculated in advance for various combination of network resistances.In the case of the occurence of an abnormal airway, it is generally impossible to get the accurate airflow distribution by an ordinary method for ventilation analysis method, because the value of the changed resistance there is unknown. However, it is proved that the correct airflow distribution can be obtained, if measured airflow data are introduced in the ventilation network analysis method proposed in this paper.