Study On The Fire Source Combustion Characteristics And Effects On Leeward Tunnel During Mine Fire Period

Mine laneway fire was influenced by tunnel space relatively narrow and closed, aswell as the oxygen is short supply, can cause significant property loss of life usually. Formine tunnel fire, study on the fire combustion characteristics and fire area resistance, aswell as the influence with the leeward tunnel during fire combustion has importanttheoretical and practical significance for the reasonable evaluation of fire risk and scientificanalysis ventilation system reliability under the fire area condition, in addition reasonablecontrol direction of wind flow and grasps the temperature and air velocity of smoke flowthrough the tunnel during mine fire rescue.（1） In this paper, experiment measured the wind flow pressure and temperature ofeach measuring point, in addition the static pressure difference between points before andafter the fire area and leeward gas components are determined. The fire resource heatrelease rate equation based on oxygen consumption principle and the temperature fieldequation in leeward tunnel of fire resource, as well as fire area resistance equations byin-depth study and calculation methods are determined. Fire heat release rate, fire arearesistance of different time and temperature field distribution are determined during fireburning.（2） Fire heat release of different time is analyzed during firing in tunnel, that changeprocess has three stages. First is the rapid development stage, the change stage fire quicklyreach the maximum heat release rate. Followed by steady stage, the stage fire resourcecombustion with maximum heat release rate, the duration of the stage is greater thandevelopment but shorter than decay stage. Finally is slow attenuation stage, the stage fireheat release rate decreases over time gradually, the duration accounts for two-thirds of thewhole combustion process roughly. Between the maximum heat release rate of fireresource and wind initial dynamic pressure conforms to a linear equation and therelationship were identified. Coal and timber areQ_max0.0035Hv0.0175and Q_max=0.0039H_v+0.06respectively.（3） According to the fire heat release rate t²model theory analyzes the heat releaserate calculation results, the coal and timber heat release rate t²model are determined, thedevelopment and decay coefficient of coal are12kW/min²and0.12kW/min²respectively,timber is12kW/min²and2.2kW/min²respectively. Integral operation of fire heat releaserate t²model established the total heat output equation. The coal unit mass heat output isobtained according the total heat output divided by the quality of the combustion coal,calculated the unit mass of coal and timber heat output are432kJ and432kJ respectively.（4） The experiment identified the experimental coefficient Kcof temperature fieldequation in the leeward tunnel, namely Kc=15²0in fire development stage, Kc=10¹5infire stable stage, Kc=20²5in fire decay stage. Section temperature t²model theory isstudied, and the section3temperature t²model is established, its development coefficientand decay coefficient are0.251K/min²and0.0708K/min².（5） Temperature field change rule of fire source leeward is analyzed, the results showthat at the developing and stable stage of tunnel fire, the temperature of airflow in thedownstream tunnel will decline with the increasing of distance to the fire field. At thefailing stage of fire, because of fire is unstable and flesh air inflow, there is an area whichthe temperature decreases fastest in the downstream tunnel. The area starts from the placewhich is closed to the fire field and moves to the place where is far away from thedownstream tunnel gradually.（6） Fire source total resistance and fire area resistance change law are analyzed. Theresults indicate that fire resource total resistance by the hard resistance, frictional resistanceand fire resistance constitutes in the process of fire burning. Hard resistance decreases withthe carburant size reduce gradually, frictional resistance remains unchanged. Fire arearesistance increases in the development and the stable combustion stage gradually, indecay stage begins to shrink and tends to zero. Fire area resistance reaches maximum value71.5Pa when the temperature increased to351.6K and air volume of roadway for0.419m³/s.