Study On Fire-induced Smoke Propagation Characteristics And Control Technology In Largely Inclined Roadway Of Mine

In recent years,underground mine fire have occurred more frequently in our country.Owing to many fire hazards underground,the long-narrow and confined structure and the wide range of fire impact,the prevention and rescue of mine fire accidents cannot be ignored.Due to the production demands and geological conditions,there are inclined drifts in the mine with slopes ranging from 0 to 30°.In inclined laneways,the greater the slope,the stronger fire-heating air pressure.And it can cause disorder in airflow and accelerate the spread of fire.In this paper,Fire Dynamics Simulator(FDS),a fire dynamics software,was used to investigate the smoke propagation characteristics and critical velocity in largely inclined mine laneway.And the smoke spread characteristics with tilted angles at 0-30° under different ventilation methods were analyzed to provide theoretical references and technical supports for mine fire control practice.The main research contents are:1)The distribution of longitudinal smoke temperature and flow velocity along inclined laneways with natural ventilation were analyzed,then a new correlation of the maximum smoke temperature beneath the ceiling with large slope greater than 10°was proposed.Comparing the smoke temperature among different tilted laneways,it is concluded that the floor temperature in laneways tilted at 0-30° is higher,indicating that the higher temperature smoke in near field of fire source declines to floor in largely inclined laneway,which seriously threatens the lives of crapped people.The decrease of smoke temperature along the ceiling can be correlated well by the sum of two exponential functions when the slope is below 10°.And the rate of decay can be affected by different HRR when the slope is more than 10° While the HRR is stronger,the decay rate is more suitable with single exponential decay.2)The maximum temperature and longitudinal attenuation characteristics below ceiling in tilted laneway fires with longitudinal ventilation were analyzed,then a new correlation of the maximum smoke temperature in longitudinally ventilated laneways with slope greater than 10° was proposed.The model analysis results show that with the increase of the laneway slope,the temperature rising gradient in the vertical direction decreases,and the higher temperature smoke in near field of fire source declines to floor.The entire roadway is filled with the hot smoke.The temperature attenuation characteristics along the ceiling with large roadway slopes can be correlated well by the sum of two exponential functions.And according to the analysis of the dimensionless longitudinal temperature,the longitudinal smoke temperature distribution downstream the fire source can be divided into two regions with(x-x0)/H-5 as the limitation.3)Focusing on the longitudinal ventilation control of the smoke in largely inclined laneways,the effect of tilted angel on critical velocity in mine laneway fires was studied and the critical velocity for horizontal and inclined laneways were obtained.At the early stage of fire development,the longitudinal ventilation force in the slopping laneways dominates so that the trapped people downstream are more dangerous.However,after a period of time,the fire-heating air pressure reverses the direction of gas flow,threatening the safety of people upstream.